O and P class destroyer (1941)

The O and P class were wartime destroyers of the British Royal Navy ordered in 1939, and first ships in the War Emergency Programme. The O was the first, and the P-class, the second Emergency Flotilla, to act as convoy escorts. Postwar, some were also converted as ASW frigates (second-rate) as well (Type 16). The O and P class were a near-repeat of the J class although they were smaller, and had more sheer forward as well as were the first using the Fuze Keeping Clock HA Fire Control Computer. They also diverged greatly by their simpler armament, from three twin to four or five single mounts, sometimes combining 4.7-in low angle and 4-in HA mounts. Four O-class were also delivered as minelayers.

Development

The first so-called “Intermediate destroyers” in concept went back to Admiralty discussions in 1938. These new destroyers would find a place and intermediate position between the large fleet destroyers of the Tribal class, financially unsustainable, and small escort destroyers made for pure escorts work, the Hunt class. These destroyer would be simplified in construction and armament to be built more quickly and cheaply, to replace the now outdated legacy “V” and “Modified W” classes of 1918-19.

The starting point were the recent “J” class destroyer which already were a reaction to the Tribals, being smaller and cheaper. The same hull and machinery was retaken almost without changes albeit slightly modified dimensions and a better forecastle shape, with a reworked sheer and slope forward to regain seaworthiness as the J class had a tendency to “plough” in heavy weather. This class was also planned to use alternaitve armaments, due to weapons manufactiring bottlenecks:

They were planned to use both single and twin 120mm mounts. However for simplification, the latter was abandoned. In this ultimate “intermediate” destroyer, displacement was toned down to 1500t with an economical armament of four single 120mm mounts, pompom, quadruple Vickers 12.7mm MGs and quadruple TT, and larger DC stowage. Of course by the time they were completed in 1942, this dramatically changed again.

An order for 8 ships of first “O” class in two batches was passed the very same day Britain declared war on Germany, on 03 September 1939. This was the very first naval entry of the new “Emergency war program” and thus, the O class became the “1st emergency flotilla”. Later another order for a repeat of eight ships was passed a month later; These became the “Р” class or “2nd emergency flotilla”.

War experience however soon posed the question of the adequacy of the AA armament, so already by the summer of 1940 specifications changed: One torpedo tubes bank was dropped and replacved by a twin 4-in HA (102mm) AA gun mount and the Vickers quad was later dropped and replaced when completed in 1942 by single 20 mm Oerlikon A guns. Some even wanted to rearm half these ships by twin 102mm mounts. By February 1941 eight of these ships, six of the “Р” class and two of the “O” class interchanged names when rearmed from 120mm to 102mm AA guns. Since these were lighter, this gave margin to reinforce their anti-submarine armament.

By March 1941 it has been decided to complete four “O” class as minelayers and their artillery was changed from 4.7-in (120mm) to lighter single 4-in, from seven to four, the second torpedo tubes bank back in place, and rails for 60 mines mounted at the stern deck, runing from the aft funnel. There was still the provision to mount more mines, removing the TT bank once more and a 102mm gun to compensate.

Design of the O class

The O-class were laid down in two groups of four, the first coming with 4.7 inch guns on single low-angle mounts elevating to 40 degrees, but one of their TT banks (the aftermost) was replaced by a single 4-inch anti-aircraft gun for AA defence. The second group had instead 4-inch (102 mm) guns in single high-angle mounts as dual-purpose while being fitted in addition as minelayers and thus they differed by their flat “beaver tail” stern to better drop mines, but the rails were only optionally mounted.

Indeed, if they had these mines, the weight penalty forced the landing of their “Y” (aftermost) main gun, all well as their remaining torpedo tubes banks and depth charges. The anti-aircraft armament as designed for both groups was the same, one quadruple QF 2-pounder “pom pom” and two quadruple 0.5-inch Vickers A/A machine guns. The latter was clearly outdated in 1942, so their were replaced by 20 mm Oerlikon guns when available, six installed total including two in th former platforms for the Vickers quad, abaft the bridge.

The O class all survived the war whereas five took part in the Battle of the Barents Sea, in which Onslow being damaged but survived. After it, they all received upgrades ad radar refit for which they traded their tripod masts for lattice masts, which had greater strenght.

They were built at the following yards:

John Brown: Acasta, Achates, Basisisk, Beagle (all with Brown_Curtiss turbines instead of Parsons)
Thornycroft: Acheron, and the two Canadian ones, HMCS Saguenay and Skeena.
Hawthorne Leslie: Active, Antelope, Blanche, Boadicea
Scotts: Anthony, Ardent
Vickers-Armstrong: Arrow, Keith
Palmers: Boreas, Brazen
Swan Hunter: Brillant, Bulldog

Hull and general design

The O/P class were indentical with thelselves and the J-class. As often in a wartime emergency, repeats were the easiest way to produce a design without much delays. The modifications only concerned some modularity in the gun mounts designs fore and aft to accept either 4.7 or 4 inches/45 HA QF depending on the batch. The previous J-class (K and N as well) had three twin BL 4.7 inches/45 Mark XII that were quite heavy and the overall design was seen as overweight, despite being a reaction to the Tribal class.

Emergency was thus also in the armament. Just for the sheer number of hulls needed, to replace all vintage V-W destroyers, the design opted for a return to single mounts, more available and lighter, with just a swap option between ships. Some would have the 4.7 inches Mark IX, others the dual purpose 4-in/45 Mark V HA, but all would have their pair of quadruple TT banks, alsthough this was later change. The AA and depht charge provision did not change much.

The new destroyers displaced 1,690 tons (1,717 tonnes) standard or 1,640 tons (1,666 tonnes) depending on the batch and on average 2,250 tons (2,286 tonnes) full load. This was less than the J/K class. They ended shorter as well at 345 ft (105 m) overall versus 356 ft 6 in (108.5 m), for a reduced beam as well, down to 35 ft (10.7 m) instead of 35 ft 9 in and a draught much reduced to 9 ft (2.7 m) versus 12 ft 6 in or 3.8 m. The O class equipped with the 4.7-in guns displaced 1,610 tons (1,636 tonnes) standard and 2,270 tons (2,306 tonnes) full load. The P class were even rated at 1,540 tons (1,564 tonnes) standard and 2,220 tons (2,255 tonnes) full load.

The general hull outlook was overall similar, albeit the forward sloped deck was redesigned as well as the forecastle bow flare for better seakeeping. This, cimbined with a return to lighter single mounts made a considerable difference in service. When the J/K/N were nose-heavy
and ploughed in heavy weather, the O/P class remained well-buoyant and “dry”, facilitating the work of the gunners and clearning out the bridge from massive splashes.

On that note, the O/P class had the same general superstructure design as for the K/K/N except for the mounts. Their racy profile had the same semi-clipper bow style, a rounded bow and near-constant beam. The single funnel was raked and placed just at the break of the forecastle, and the bridge was of the same wedge type standardized much earlier. The two TT banks were placed aft amidship with an intermeduate platform hosting a searchlight, small mast (to which was flew the main battle pennant) and to which were attached the wireless radio cables. On either side were located the Vickers quad HMGs. The single 40 mm pompom was located on a bandstand immediately aft of the funnel. Normal Complement was 176 officers and ratings, but the two leaders, Onslow and Pakenham, had an extra staff crew with the flotilla captain(D) plus extra accomodations for a crew of 217. Otherwise, the leaders were just the same as regular destroyers in their own class.

Powerplant

Propulsion was essentially a repeat of the J/K/N class, with two shaft propellers, 3-bladed bropnze, fixed-picth, driven by Parsons geared steam turbines, in turn fed by steam coming from two large Admiralty three-drum water-tube boilers for a total output of 40,000 shp. This procured the O/P class a top speed in excess of 36.75 kt. Some reached 38 knots on sea trials. In regular service, 35 knots was the norm.
Range was about the same as before at 3,850 nmi at 20 knots cruise speed based on fuel tanks capacity of 472 tonnes. Both O and P classes had not noted differences in performances despite diverging displacements.

Armament

The “baseline” armament for the O-class, notably for the firs batch of four (Obdurate, Obedient, Opportune, Orwell), was essentially the same as for the next eight ships of the P-class with four QF 4 in Mk.V (102 mm L/45), all single mounts HA Mk.III. Four were placed in superfiring positions fore and aft like earlier classes. The had their two twin quadruple TT banks, and a squat stern for laying mines, being equipped with rails on either side of the deck.

The second batch (Offa, Onslaught, Onslow, Oribi) had a fifth gun installed in place of the aft TT bank, leaving just one forward. In addition to this “B” 4-in Mk.V (102 mm L/45) mount HA Mk.III aft amidship, the four superfiring positions were swapped to the QF 4.7-inch (120-mm) Mk IX guns on single mounts CP Mk.XVIII with box-like masks. These low elevation mounts were intended for A/S work only. This second batch of O-class also only had a single TT bank to make room for the extra 4-in/45 HA. The P-class were like the early O class batch but with an extra 4-in/45 QF Mk V instead of the aft TT bank like the second O-class batch.

What did not change on all these three sub-variants was the AA provision, made of a single quadruple QF 2 pdr Mk.VIII (40 mm L/39) mount Mk.VII on a bandstand just aft of the funnel. If initially two quad Vickers 0.5 inches AA were planned, installed on the platform between the two TT banks (or A-bank and B-4-in/45 mount), they were removed at completion in 1942 and swapped for two single QF 20 mm Oerlikon on single mount P Mk.III and later during the war, to two twin, with the remaining four single mounts located on the bridge’s wings and lokely aft, close to “X” mount. The quad torpedo tubes were for torpedoes Mk.IX. The four throwers and two racks were for 70 depth charges.
The minelayers of the seocnd batch had squat sterns and up to 60 mines, if mounted.

BL 4.7 inches/45 QF Mark IX

The prototype was mounted on HMS Mackay. It was installed onn the A through I, O and Q through W destroyer classes as well as the ex-Brazilian (H class) and ex-Turkish (I class). The Mark XII were the twon mounts unique to the J/K/N. They had a wide and roomy gun shield, albeit the rear was open to the elements and enemy fire. It was much lighter than the twin mounts.

Specifications 4.7-in/45 QF Mark IX

Gun weight 2.963 – 2.984 tons (3,011 – 3,032 kg), 220.62 in (5.604 m), bore 212.6 in (5.400 m).
Rate Of Fire on the CPXXII single Mounting was 10 – 12 rounds per minute with trained gunners.
Shell: HE 50 lbs. (22.68 kg) or SAP 15 in (38 cm), same weight.
Muzzle Velocity 2,650 fps (808 mps). Typically these destoryers carried 200 SAP rounds and 50 HE rounds plus 50 star shell per ship.

BL 4 inches/45 HA Mark V

The base model existed from 1914 and overall 944 were manufactured. The Mark V was the last evolution in WWI, also used in WW2. Its main difference was new shells, replacing the 31 (3 c.r.h.) by the 4.38/6 c.r.h. Muzzle velocity was the same at 2,350 ft/s (720 m/s) but the range was imprpved from 28,750 ft (8,760 m) to 31,000 ft (9,400 m). Flying time to 15,000 ft or 4600m at 55° was 12.3 seconds, making the fuze setting quite important for accuracy. The four mounts had light shields enabling an elevation up to 80°, and the single “B” mounst aft amidship had none. The mount gave them a range of 31,000 ft or 9,450m. Agains ships at 44° they could hit targets at up to 16,430 yards (15,020 m).

Specifications 4-in (101.6 mm)/45 Mark V

Mass, barrel & breech 4,890 lb (2,220 kg), 15 ft 8 in (4.8 m) oa, Bore 15 ft (4.6 m) 45 cal.
Shell: 31 lb (14.1 kg) fixed QF or Separate-loading QF, HE 53.5 lbs. (24.26 kg), SAP 56 lbs. (25.4 kg) and Shrapnel
Breech horizontal sliding-block, hydro-pneumatic/hydro-spring recoil 15 inches (380 mm)
Muzzle velocity: 2,350 ft/s (716 m/s). Filling Lyddite, Amatol 5 pounds (2.27 kg).

2-pdr/39 Pompom QF Mk VIII

Specs:

Shell: 2 lb. (980 g) or 1.8 lb. (820 g) HV
Performances: 115 rpm fully automatic at 2,040 ft/s (622 m/s) or 2400 ft/s (732 m/s) for HV
Effective Range: 3,800 yards (3,475 m) or 5,000 yards (4,572 m) HV, Ceiling HV: 13,300 feet (3,960 m)

21-inches torpedo tubes

The greater change was going from triple to quadruple torpedo tubes banks. This really set apart the interwar British destroyers from all those prior and setup a new standard.
They were placed on a deck top plaform, reloadable thanks to cranes. The model used for the A and B class destroyers were relatively old. It’s unlikely oters were fitted as in WW2, these tubes were removed, first the aft bank, then the amidship one to make room for extra AA and ASW. The long range mode was so slow it made the torpedoes unusable against anything but old battleships and civilian vessels. The 40 knots mode however obliged to close the target to less than 5000 yards to be of use, a dangerous proposition unless in heavy weather and fog/night.

Specs 21 inches Mark V (1918)

Weight: 3,828 lbs. (1,736 kg)
Length: 23 ft 3 in (7.086 m)
Explosive Charge: Unknown, c600 Ibs. or 250 kgs TNT
Range and Speed settings: 5,000 yards (4,570 m)/40 knots or 13,500 yards (12,340 m)/25 knots
Power: Wet-heater

Depth Charges

Mark VII depth charge thrower being reloaded.

The usual set comprised from two to four Mark II Depth Charges Throwers (DCT) aft on the poop deck, facing either side, and one to two Depth Charge Racks (DCR) at the stern. Each carried five charges but they were railing to the aft superstructure for a total storage of 40 more DCs. Reload was made by hand, using winches, always a dangerous task with a rolling deck washed by waves. These depht charges were of the standard British type, meaning it was the Mark VII: In entered service in 1939, weighted 420 lbs. (191 kg) and carried a 290 lbs. (132 kg) TNT with a sink Rate or Terminal Velocity of 9.9 fps (3.0 mps) with a max setting at 300 feet (91 m) later 500 feet (182 m).

It’s possible they were later upgraded to the the Mark X (1944) and the Mark X*. The X** was not introduced in service in 1945 despite its great depth (down to 1,500 feet (457 m)). Squid and Hedgehog made them obsolete. There are doubts also if the Mark VII Heavy studied from 1940 and proper to depth charge launchers were used aboard, outside experimentally. Weighting 420 lbs. (191 kg) with a 290 lbs. (130 kg) TNT charge, they had a sink rate/terminal velocity of 16.8 fps (5.1 mps) and a 300 feet (91 m) max setting, helped with a 150 lbs. (68 kg) cast-iron weight attached. The idea was to reach the U-Boat faster, and it was claimed it could split open a 0.875 inch (22 mm) hull at 20 feet (6.1 m), or force to surface at 12 m or more. The game changer was a minol charge (1942) for better results, with a 30% increase.

Fire control: Fuze Keeping Clock HA Fire Control Computer

The Fuze Keeping Clock (FKC) was a simplified version of the High Angle Control System analogue fire control computer. The FKC MkII was installed first on the 1938 Tribal class, later variants on destroyers such as the J/K, L/M, and O/P. The FKC MkII was a non-tachymetric anti-aircraft fire control computer, able to accurately engage targets flying at 250 knots (460 km/h; 290 mph). The Mk V Fuze setting tray was combined with a 4 in (102 mm) anti-aircraft (A/A) round and the fuze timing data was received via electrical signals from the FKC, displayed on a dial. The operator matched these settings on the tray’s own dial, adjusting the clockwork in the A/A warhead to the calculated flight time.

Sensors

Type 271 radar

The Type 271 was a British centimetric (~10 cm/3 GHz) naval surface-search radar introduced in 1941, widely used by Royal Navy escorts to locate surfaced U-boats, even their periscopes (3 miles (4.8 km) U-Boat surfaced, or a periscope at 900 yards (820 m)). It was one of the first practical microwave radars small enough to fit on small escorts.
It was used for short-range surface search and as submarine-hunting radar. A CT could be picked up at a few miles, a periscope at several hundred yards, useful in the night. It improved resolution over older and longer-wavelength radars at night and low-visibility.
Frequency/wavelength: ~2.95–3.0 GHz (~10 cm band).
Pulse repetition: ~500 pps; pulse width commonly 0.7–1.5 µs in various marks.

Power: early sets ~5–7 kW; later “Q/Mark IV” and other upgraded models used much higher magnetron output (tens to hundreds of kW peak), increasing range and stability.
Antenna: small stacked “cheese” (sliced-parabola) antennas in a protective perspex lantern — compact enough for small-ship mounting.

Display: early sets gave range/angle on A-scope; later Q-models added a PPI (plan position indicator) for easier tactical use.
Derived/related sets: Type 272 for destroyers, less successful and Type 273 for cruisers and battleships. Replaced by the Type 276/277.

Type 285 radar

The Type 285 was a fire-control radar, same generation of centimetric radars, transforming naval gunnery and air defense in WW2.
It was used for High-Angle (HA) anti-aircraft directors and installed on the batches armed with 4-in/45 HA mounts as main armament, plus the ones swapping a TT bank for a single mount. It was deployed just as the O-P class were completed. This was an integral part of the High-Angle Control System (HACS), notably combioned with the Fuze Keeping Clock system, being fitted on new destroyers from mid-1941 onward, retrofitted to existing destroyers when possible. Frq 600 MHz, power 25 kw, range 18,000 yd (16,000 m), ceiling 15,000 ft (4,600 m) accuracy 150 yd (140 m). Later variants enable tracking targets at 500 knots (930 km/h; 580 mph), combined with Gyro Rate Units for tachometric capabilities, greatly improving ranging and accuracy.

Type 286P radar

Type 286: Naval air search radar, first destroyer set, very crude, not rotating. Full data 286P: rotating antenna, better bearing accuracy of 3-5 degrees. The Type 286 was a British naval radar derived from the RAF’s ASV Mark II radar system. Initial versions such as the Type 286M had fixed antennas, so the entire ship was turned to angle the radar beam in any direction.

The Type 286P variant had at last a rotating antenna, improving bearing accuracy to about 3–5°. It worked in the VHF/metric waveband (around 214 MHz), similar to other naval radars of that family. It was used primarily for surface-warning and as target indication rather than fire control. Since it was relatively low in frequency and had broad beamwidths, resolution and detection of small targets was poor. It used beam-switching on the receiving aerial (in earlier Type 286 versions) to help with bearing information. It was replaced in time by the Type 291 (1944-45).

Sonar Type 144

From 1943, range 2500 yards (2300 meters) to 3000 yards (2700 meters), integrated into the fire control and coupled with Hedgehog. 1st with bearing recorder, automatic scanning, turning 5 degrees after each ping, often coupled with the Type 147 “Sword” depth finding sonar with a beam steerable vertically. Also coupled with the Q attachment reducing the under hull blind spot. 60° deep vertical beam, trained with the main Type 144 transducer.

⚙ specifications O class 4.7-in 1941
Displacement	1,610 tons (1,636 tonnes), 2,270 tons (2,306 tonnes) FL
Dimensions	345 x 35 x 9ft (105 x 10.7 x 2.7 m)
Propulsion	2 shafts Adm. 3-drum WT boilers, Parsons GST 40,000 shp
Speed	36.75 knots
Range	3,850 nmi at 20 knots
Armament	4× QF 4.7-in Mk IX, 1× Mk.V L/45, 1×4 2 pdr pompom, 6x 20 mm Oerlikon, 1×4 21-in torpedoes
Sensors	Type 271, 272, 285, 291 radars, type 144 sonar
Crew	176 (217 in leader)

⚙ specifications O class 4-in 1941
Displacement	1,540 tons (1,564 tonnes), 2,220 tons (2,255 tonnes) full load
Armament	4× QF 4 in/45 Mk.V, 1×4 QF 2 pdr, 6x 20 mm Oerlikon, 2×4 21-in torpedoes, 60 mines*

*All of the O-class ships with 4-inch armament were fitted for minelaying.

Wartime Modifications

In 1943 all the ships having single 20mm/70 abaft the briodge were replaced by twin Mk II/IV.
In 1943-1944 they also all received two more 2 DC Thrower with 60 DCs. They also traded their type 286P radar for a type 290 radar and until 1945 those with the type 286P or type 290 were upgraded again to the type 291 radar. A few also obtanined the type 272 radar. HMS Offa, Onslaught, Onslow lost their aft 4-in/45 HA for the return of their 21-in TT bank.

After the war, Offa, Onslaught and Onslow ended the war with their four 4.7-in/45 CP Mk XVIII, a quad pompom Mk VII, two twin 20mm/70 Mk V and two single 20mm/70 Mk III Oerlikon AA guns, all their torpedo tibes, four DC Throwers and two 2 DC Racks for 60 depht charges. Some possiblu retained their Type 271 and type 272 radars, but the norm was a type 285 and type 291 radar as well as the type 144 sonar.
HMS Oribi kept her 4-in/45 HA Mk III instead of her 21-in TT bank and the same. Obdurate, Obedient, Opportune and Orwell had both TT banks mounted.

Career of the O class

Career of the O class

HMS Onslow (Flotilla Leader) laid down as HMS Pakenham at John Brown on 1 July 1940, then swapped for the O-class and renamed, launched on 31 March 1941 and commissioned on 8 October 1941. First to be ordered in the Second Emergency Flotilla as Packenham on 2 October 1939 (contract price of £416,770 (excluding armament) but renamed in early 1941 and thus, became leader of the 1st Emergency flotilla. She was damaged by a bomb during in an air raid on 3 June 1941 which delayed completion for a month, completed by 8 October 1941.
With the Home Fleet she entered Arctic convoys after working-up, Onslow as leader of DesFlot17. By November 1941 with Offa and Berwick, joined Arctic convoy PQ 4 until relieved on 27 November to Arkhangelsk, she proceeded instead to Murmansk, attacked by German bombers in the Kola Inlet on 28 November, and she had near miss damage.

On 24 December she left Scapa Flow with HMS Kenya, Offa, Oribi, Chiddingfold and two landing ships for Operation Archery against Vågsøy and Måløy on 27 December. While Commandos landed, Onslow and Oribi attacked a coastal convoy and sank the German merchants Reimar Edward Fritzen, Norma, Eismeer and Anita M Russ, boarding the Vorpostenboot (armed trawler) Föhn and captured coding wheels/bigram tables for the Enigma machine, and later more codebreaking material when capturing the Donner and on Anhalt.

On 1 January 1942 she rescued 23 survivors from the merchant Cardita torpedoed by U-87. In early March, she was in distant escort to Arctic Convoys QP 8 and PQ 12. Tirpitz sortied, but poor weather ensured she never found the convoy and the Home Fleet forces never found her in return albeit she was spotted and attacked by aircraft from Victorious. Later she escorted Arctic Convoys PQ 13 and PQ 14 and on 21 May, with PQ 16 of 35 she left Reykjavík, with 5 other DDs in close cover and a covering force in she was, with three cruisers and her unit, Onslow, Offa and Oribi from 23 May. She was ordered then to escort convoy QP 12 which was unharmed.

In June 1942, she was sent to Mediterranean for Operation Harpoon to Malta simultaneous with Operation Vigorous from the east. Onslow was in Force W with Malaya, Argus and Eagle, three cruisers from 12 June, until turning back to the Strait of Sicily on the 14th. Back home she was sent to the arctic convoy PQ 17/QP 13. The first was scattered based on false intel of Tirpitz being out, resulting in heavy losses (24 of 25 sunk). In August 1942 Onslow was occupied by return convoys from the Med to British waters via Gibraltar but also detached for Operation Pedestal.
By September 1942 she escorted PQ 18 in addition to HMS Avenger, and 16 destroyers led by HMS Scyllan themselves backed up by cruiser and battleships. She was part of the closer “fighting Destroyer Escort” from 9 September, attacked on13 September. On 14 September, a Swordfish from Avenger surprised U-589 surfaced. Onslow made a depth charge attacks on three hours, sinking her. They stayed with the convoy until 16 September, and transferred to QP 14 from 25 September. 13 ships/40 were sunk still, for the cost of 3 U-boats, 41 German aircraft. 4 more were lost from QP 14.
On 8 November 1942 she was sent to take part in Operation Torch, escorting follow-up convoys.

In December, she was part of the Arctic Convoy JW 51B from Xmas Day 1942 under Captain Robert Sherbrooke, leading 6 destroyers, 2 corvettes, 1 minesweeper, 2 armed trawlers for 5 merchant ships. Oribi and trawlers were separated by bad weather. On 30 December, they were ambushed by U-354. They were attacked also by Lützow and Admiral Hipper plus six destroyers from Altafjord, which split into two, Hipper and three destroyers northwest, Lutzow, three destroyers south in a pincer on 31 December in what became the battle of the Barents Sea. Sherbrooke led dummy torpedo attacks against Hipper to force her out while laying a smoke-screen. After 40 minutes, Onslow was hit by three shells from Hipper, near missed by a fourth, badly damaged, loosing two guns and with a large fire, 17 killed, 23 wounded including Captain and Flotilla commander Sherbrooke. Achates was sunk by Hipper, Obedient damaged, but the arrival of Sheffield and Jamaica turned the tide, damaging Hipper, sinking DD Friedrich Eckoldt. The convoy was saved. The minesweeper Bramble was sunk as Achates and Sherbrooke was awarded the Victoria Cross.

After repairs at Murmansk, Onslow returned to Britain with Convoy RA 52 by late January 1943 for full repairs at Kingston upon Hull and back in April. By November 1943, she was in distant support for Convoy RA 54A back from Russia and escorted Convoy JW 54A on 18-24 November as well as Convoy RA 54B from 28 November to 5 December. From 22 to 29 December she joined Convoy JW 55B. Scharnhorst sortied, leading to the Battle of the North Cape on 26 December. She was back home with Convoy RA 55B on 7 January 1944.
Refitted on the Tyne (18 January to 22 February) she was back in operation from March 1944 in the English Channel, then Convoy JW 58 and RA 58 until 13 April. Next she was swapped for Channel patrol and escort. On 27–28 April 1944 she was alerted as a battle seeing 9 German S-boats attacking a US LST convoy in Lyme Bay but she arrived too late and searched survivors and bodies. On 14-15 May 1944 she escorted the HMS Emperor and Striker for the raids on Rørvik and Stadlandet. On 6 June 1944 she was deployed in the invasion force (Operation Neptune) and on 6/7 June near-missed by a bomb. On 11/12 June with Onslaught, Offa and Oribi she battled against six German S-boats. On 18 June, Onslow was hit by a German air-dropped torpedo (dud) while under repair. On 12 August she escorted the cruiser Diadem and destroyer Piorun when they sank the minesweeper Sperrbrecher 7 near La Rochelle.

In September 1944, she was back with the Home Fleet and Arctic convoys such as Convoy JW 61 in October, RA 61 in November. In December she was with Convoy JW 62 and RA 62. By January 1945 she was sent for a raid in Norway on 11/12 January with Norfolk and Bellona, with Onslow, Orwell and Onslaught. They surprised a convoy off Egersund, sank M-273, badly damaged Bahia Camarones and Charlotte, sank. By February 1945 she escorted Convoy JW 64 heavily attacked (corvette Denbigh Castle torpedoed by U-992). RA 64 was attacked in the Kola Inlet on 17 February (sloop Lark, freighter Thomas Scott torpedoed by U-968, corvette Bluebell by U-711). She rescued one man from Bluebell.

On 12 May 1945, she was part of Convoy JW 67 to Russia, and RA 67 back on 23 May. On 5–7 June 1945 she escorted HMS Norfolk, carrying King Haakon VII of Norway back from exile to Oslo. By August 1945, she took part in the first Navy week in Rotterdam with HMS Bellona, Garth and Tuna, greeted by Dolfijn and Zeehond. In November–December 1945 she became HQ for Operation Deadlight (U-boats scuttling off Ireland). In “Care and Maintenance status” at Devonport from January 1946 she was planned as a target ship but was purchased by Pakistan in 1948, along with Offa for £605,000, transferred to Pakistan on 30 September at Plymouth as PNS Tippu Sultan. In 1954 she was refitted at Malta. In 1957-1959 she was converted as a Type 16 frigate by Grayson Rollo, paid for by US MDAP, active in 1965 war, raiding Dwarka on 8 September, also the 1971 war, stricken 1980, hulked.

Offa was laid down at Fairfield on 15 January 1940, launched on 11 March 1941 and commissioned on 20 September 1941. By November 1941 she was part of the escort of Convoy PQ 4 led by her sister Onslow (see above), as the 5th Arctic Convoy, from Hvalfjord (Iceland) on 17 November 1941 to Arkhangelsk on 28 November 1941. On 14 September 1942 under Lt.Cdr. R.A. Ewing she took survivors from the tanker Atheltemplar, torpedoed by U-457 south west of Bear Island. On 26 January 1944 she took survivors from the Fort Bellingham, torpedoed by U-957 in the Barents Sea, North Cape. Fast forward (same career as her sister) she took part in the King’s Birthday celebrations at Kiel on 2 June 1945 whtg HMS Obedient
In 1946 she became target ship for submarines, was placed in reserve at Devonport in February 1948 but by April she was refitted at Devonport before transfer to Pakistan in 1949 as Tariq, sold for scrap in 1959.

Onslaught (ex-Pathfinder) was laid down on 14 January 1941 at Fairfield, launched on 9 October 1941 and commissioned on 19 June 1942 with the 17th Destroyer Flotilla, Home Fleet. She took part in convoy escort starting with the Arctic convoys and a few in the Atlantic. By 1944 she was in patrol duties in the English Channel, notably taking part in night patrols against S-Boats during the the Normandy landings in 1944.
Still commissioned by September 1945 she was used for training duties at Portsmouth Gunnery School HMS Excellent. In December seh took part in Operation Deadlight on the Northwestern Approaches. Between 1946 and 1949 she became a submarine target ship in the Clyde. Paid off early in 1950 she was on the Disposal List until transferred to the Pakistan Navy on 3 March 1951 as PNS Tughril. In 1957 she was converted at Liverpool to a Type 16 ASW frigate and active until 1975, seeing two more wars. She was scrapped in 1977.

Ordered as HMS Observer when laid down 15 January 1940, she was renamed and launched on 14 January 1941, commissioned on 5 July 1941. On 4 August 1941 she hosted and carried PM Winston Churchill and senior officers from Scrabster, Scapa Flow, to HMS Prince of Wales, for passage to Newfoundland a secret meeting for signing the Atlantic Charter with the US President. She took part in Operation Archery on November 1941 on Norway, and she assisted in bringing Norwegian nationals home, escapng the German occupation.

She took part as her sisters in DesFlot 17 in most Arctic and North Atlantic convoys such as ONS 5 in May 1943. At 03:00 on 6 May 1943 her radar operators picked up U-125 in thick fog. She surprised and rammed her. Disabled, she was unable to dive. 54 minutes later, the Flower-class Snowflake and Sunflower closed to 100 yards, to seen the crew evacuating her scuttled the boat. The captain of Snowflake signalled Lieutenant Commander Robert Sherwood on Oribi to pick them up. He replied “Not approved to pick up survivors.” Snowflake and Sunflower returned to the convoy, and the crew of U-125 never survived. Postwar, Oribi was transferred to the Turkish Navy in 1946, renamed Gayret, replacing I-class destroyer requisitioned by the RN and lost during the war. As D15 she served as a headquarters ship.

Obdurate was laid down at Denny on 25 April 1940, launched on 19 February 1942 and commissioned on 3 September 1942. She escorted Arctic convoys in 1942 and 1944, Atlantic convoys in 1943, and was present at the Battle of the Barents Sea. In December 1942, while ecorting JW 51B, she was hit by the German heavy cruiser Admiral Hipper in an homeric battle. On 25 January 1944, she was torpedoed by U-360, using a new GNAT acoustic torpedo southeast of Bear Island, while ecorting convoy JW 56A. Howeve rher bulkheads held up and she managed to followed the convoy until provisional repairs were done, and made the trip back for full repairs.

In 1945 she escorted Norfolk with King Haakon VII back to Norway. This was followed by post-war German waters patrols. On 14 July 1945 US president Harry Truman went to Obdurate from USS Philadelphia in the English Channel for his trip to the Potsdam Conference. In 1946 she was used for torpedo training at Portsmouth. In 1948 she was placed into reserve at HMNB Portsmouth. She was refitted at the Tyne in 1949-1950 and back in reserve at Chatham 1950-1952. In 1952-1956 she was part of the Nore squadron. In 1953 she she took part in the Fleet Review for the Coronation of Queen Elizabeth II. In 1957-1959 she was in reserve at Portsmouth and in 1959, used for tests at NCRE Rosyth. She was sold in 1964, BU at Inverkeithing from 30 November 1959.

Obedient was laid down on 22 May 1940 at Denny, launched on 30 April 1942 and commissioned on 30 October 1942, with the 17th Destroyer Flotilla, Home Fleet. Like her sister she was present for most Arctic convoys in 1942 and 1944, Atlantic convoys in 1943 and the Battle of the Barents Sea in 1942. In June 1944 she patrolled day and night the English Channel before and during the the Normandy landings. In April 1945 she was converted as initially planned, as a mine-layer, mining the Northwestern approaches. She was present for the King’s Birthday celebrations at Kiel on 2 June 1945 with HMS Offa.

In August 1946 she was in refit but took part in Operation “Deadlight”. She was placed at the Portsmouth Local Flotilla and Torpedo School. In Reserve from October 1947 at Sheerness she was refitted in 1949, re-commissioned on 17 October 1952, Portsmouth Local Flotilla. In 1953 she was present for the QEII Coronation Fleet Review. After July 1953 she was in Air-Sea rescue duties for carriers in the English Channel. She was replaced in the Reserve Fleet at Chatham by December, recommissioned for tests by February 1956 and back at Chatham. Proposed for conversion as ASW frigate but not acted upon and instead, laid-up in Reserve at Hartlepool by 1957. On the Disposal List in 1961, sold BISCO, Hughes Bolckow, BUt at Blyth from 19 October 1962.

Opportune was laid down at Thornycroft on 28 March 1940, launched on 21 February 1942 and commissioned on 14 August 1942. Completion was delayed by damage resulting from a German bombing in 1940, impacting the whole shipyard and delivery of components. She entered the 17th Destroyer Flotilla, Home Fleet and on trials, escorted convoy PW-202 to Bristol. Next she escorted the Arctic convoy PQ-18 to Murmansk. On 20 September she assisted HLS Somali, torpedoed by U-703 as well as Eskimo, Intrepid and the trawler Lord Middleton but rough seas got her still on 24 September. Opportune carried survivors to Scapa. By October 1942, she escorted Scylla to Gibraltar for Operation Torch, and made three days of ASW patrols in the Mediterranean while on invasion day she was with Force H.
Back home she escorted HMS Duke of York and Victorious to Scapa, a voyage marked by the end of U-517, damaged and forced to surface, surrrendering to Opportune, taking POWs and landed to Greenock.

Back to Arctic convoy until December 1942 and into March 1943 she escorted JW 53 and assisted the John H. B. Latrobe from a German minefield. She joined the 5th Support Group, Atlantic, and on 25 April, helped sink U-203 with Pathfinder and aviaton from HMS Biter. On 12 May, she presumed sank U-456. Her area swapped to the Northwest Approaches and by 14 September, she escorted the PM for the Québec Conference. In October 1943 she took part in Operation Leader escorting USS Ranger on the raid to Bodø, Norway.
By 25 December, she took part in the battle against Scharnhorst, intercepting convoy JW 55B, the Battle of North Cape. Opportune, Musketeer, Virago and Matchless continued to shadow her and fired nineteen torpedoes, scoring six hits.

In 1944 she was back in Arctic convoy escort until March, then was sent against S-boat before and during the Normandy Landings. She was back to Arctic convoys, and recalled again for the invasion and in between she had a boiler overhaul and refit, assigned afterwards to TF 27, English Channel. The 28th disastrous rehearsal of Utah Beach by S-boats saw Opportune searching for thousands of US servicemen awaiting rescue. On 6 June she patrolled in the eastern English Channel but saw engagements in July and August. She was soon back to convoy escort in the Arctic, and was converted as minelayer, deployed with Force 3 off Norway. Postwar she was kept at Portsmouth for submarine training until 1950. She joined the Nore Local Flotilla, was in Reserve at Chatham from November 1952, transferred to Portsmouth in July 1953, on the Disposal List, sold to BISCO in November 1955, BU at Milford Haven from 25 November, Thos. W. Ward.

Orwell was laid down at Thornycroft of Southampton on 20 May 1940, launched on 2 April 1942 and commissioned on 17 October 1942 with the 17th Destroyer Flotilla deployed in Arctic waters. She made her first to Arkhangelsk and back to Loch Ewe in Scotland with QP 15 from 23 to 30 November 1942. By December she escorted JW 51B and on the 30th they were attacked by U-354, and soon Lützow, Admiral Hipper and six destroyers from Altafjord, attacking on 31 December (Battle of the Barents Sea). Until the arrival of Sheffield and Jamaica she put a hell of a fight, seeing Achates and Bramble sank, but she remained undamaged.

From 19 to 27 February 1943, she escorted Convoy JW 53 in severe weather until turning back. She took part in RA 53 from Kola Bay on 1 March to 10 March. She was assigned to the Western Approaches Command, 3rd Escort Group and reinforced Convoy SC 123 and Convoy HX 230 by March 1943. She was refitted from April to May 1943 at Hull. By September 1943 she was back to the Western Approaches Command and Escort Group 10, ecorting ONS 19, notably against the wolfpack Rossbach. She was ordered to SC 143 and saw the Polish DD Orkan and a merchant sunk, for three U-boats sunk. With Oribi and Musketeer she took survivors from U-643 on 8 October. Later with USS Tuscaloosa and USS Fitch, Oribi and Onslaught she took part in Operation FQ (rescuing the garrison on Svalbard on 19 October).

From 15 November 1943 to 25 November she was back in the Arctic for JW 54A to Kola Bay, and return until 5 December 1944, RA 54B. On 22-29 December this was JW 55B, later with a sortie of Scharnhorst that became the battle of the North Cape on 26 December. Next she was with Convoy RA 55B (1-7 January 1944) and refitted at Hull (2 February-13 March), and back to Arctic convoys with JW 58 (29 March-4 April), RA 58 (7-13 April). On the 23th her unit was sent to Plymouth in prepping for the invasion of France. On 27/28 April S-boats preyed on US landing craft in Lyme Bay and Orwell and Offa rushed and clashed with withdrawing S-boats, but they escaped in a smoke-screen. On 6 June 1944 she patrolled the invasion area and by September, was back with the Home Fleet and escorted Jamaica on a supply run to Svalbard. On 22-28 October Orwell escorted JW 61 and RA 61 on 2-7 November. On the 29th she collided with the submarine Volatile. Next she escorted JW 62 on 1 December and RA 62 on 10-18 December.

On 11–12 January 1945 she escorted Norfolk and Bellona for Operation Spellbinder off Norway, seeing them savaging a German convoy off Egersund. On 6 February she escorted JW 64, claimed one German aircraft shot down on 10 February. Later she was back with RA 64. On 1 March 1945 with Opportune and Obedient she was converted as minelayer for a mission in the Irish Sea on 10 March. From 12 March to 20 May, she escorted JW 65 (battle in Kola Bay) and RA 65 on 23-30 March. The Soviets were convinced to lay a deep minefield in the approaches against U-Boats. On 17 April 1945 Apollo and Orwell, Obedient and Opportune too part in Operation Trammel, covered by Dido, sent to Kola on 20 April to lay 276 deep mines on 22 April.

In February 1946 Orwell relieved Zetland on torpedo training at the Portsmouth local flotilla. In December 1947 she was paid off, B2 reserve at Harwich, but later offered and rejected for sale to Pakistan. By 1949–50 she was refitted at J. Samuel White, Cowes and by March 1950 in Category C reserve, Chatham. She was converted to a Type 16 in frigate 1952, sold for scrap in 1965.

P class:

The P class were essentially repeats of the O class, and had only the latter batch dual purpose 4 inch guns all in high-angle (HA) mounts and fitted with a new taller but lighter shield. Balance was kept and kept one torpedo tubes bank (B TT bank replaced by a 4-in gun) while having the same upgraded AA, trading their planned quand Vickers 0.5 inches AA heavy machine guns for six 20 mm Oerlikon mounts. The table below only lists true changes.

Displacement	1,690 tons (1,717 tonnes) standard, 2,250 tons (2,286 tonnes) full load
Armament	5× QF 4-in Mk.V, 1×4 QF 2 pdr Mk.VIII pompom, 6x 20 mm Oerlikon, 1×4 21-in TTs, 4 DCT, 2 DCR (70)

Wartime Modifications

In 1943-1944, Paladin, Pathfinder, Penn and Petard had their 4-in (102mm/45) HA swapped for their original quad 21-in(533mm) TT bank.
By late 1944, Petard had a swap of main guns. Instead of four single 4-in(102mm)/45, she received two twin 4-in/45 QF Mk XVI forward, plus two extra 20mm/70 Oerlikon Mk II/IV AA guns.

When the war ended, HMS Paladin and Penn had their four 4-in/45 HA Mk III and quad 40mm/39 Mk VII pompom as well as two twin 20mm/70 Mk V, two single 20mm/70 Mk III Oerlikon AA guns. They retained all their 21-in TT banks as well as their four DC Throwers, two DC Racks (70 depht charges). Their new larttice mast supported probably the type 271, type 272 but also for certain the type 285, type 291 radars and type 144 sonar. HMS Petard still had its two twin Mk XIX, quad 40mm/39 Mk VII pompom, two twin 20mm/70 Mk V, four single 20mm/70 Mk III and the same. The main artillery was the greatets difference as in the J class.

Career of the P class

Pakenham (ex-Onslow) was ordered as the P class flotilla leader at Hawthorn Leslie. She was laid down on 6 February 1940, launched on 28 January 1941 and commissioned on 4 February 1942. Disabled by gunfire from Italian Navy torpedo boats Cassiopea and Cigno off Marsala 16 April 1943 in the Battle of the Cigno Convoy, abandoned and scuttled by sister ship HMS Paladin following the action. More to come in a later update.

Paladin G69 was laid down at John Brown on 22 July 1940, launched on 11 June 1941 and commissioned in December 1941. Converted to Type 16 frigate 1954, sold for scrap in 1962. More to come in a later update.

Panther was laid down at Fairfield on 15 July 1940, launched on 28 May 1941 and commissioned on 12 December 1941. She was bombed and sunk by German Junkers Ju 87 ‘Stuka’ aircraft in Scarpanto Strait on 10 September 1943. More to come in a later update.

Partridge was laid down on 3 June 1940, launched on 5 August 1941 and commissioned on 22 February 1942. She was torpedoed by German Submarine U-565 off Oran, 18 December 1942. More to come in a later update.

Pathfinder was laid down at Hawthorn Leslie on 5 March 1940, launched on 10 April 1941 and commissioned on 13 April 1942. On 11 February 1945, Pathfinder was hit by a Japanese bomber off Ramree, and was taken out of service. She was used as an aircraft target, sold for scrap in 1948. More to come in a later update.

Penn was ordered from Vickers Armstrongs shipyard, laid down on 26 December 1939, launched on 12 February 1941 and commissioned on 10 February 1942. She was sold for scrap in 1949. More to come in a later update.

Petard was laid down on 27 March 1941 at Vickers, launched on 15 June 1942. Postwar she was converted to a Type 16 frigate, sold for scrap 1967. More to come in a later update.

Porcupine was laid down on 10 June 1941 at Vickers, launched on 31 August 1942. She was torpedoed by German submarine U-602 in the Mediterranean on 9 December 1942, breaking her in two; she was never repaired, but hulked as Pork and Pine, sold for scrap, 1947. More to come in a later update.

Read More/Src

Books

Destroyers of the Royal Navy, 1893–1981, Maurice Cocker, Ian Allan
Connell, G. G. (1982). Arctic Destroyers: The 17th Flotilla. London: William Kimber.
English, John (2001). Obdurate to Daring: British Fleet Destroyers 1941–45. Windsor, UK: World Ship Society.
Friedman, Norman (2006). British Destroyers & Frigates: The Second World War and After. NIP
Lenton, H. T. (1998). British & Empire Warships of the Second World War. NIP
March, Edgar J. (1966). British Destroyers: A History of Development, 1892–1953. London: Seeley Service
Raven, Alan; Roberts, John (1978). War Built Destroyers O to Z Classes. Bivouac Books.
Rohwer, Jürgen (2005). Chronology of the War at Sea 1939–1945: The Naval History of WW2 NIP
Whitley, M. J. (1988). Destroyers of WW2: An International Encyclopedia. NIP

Links

/uboat.net P class DDs
/uboat.net O class DDs
British Mechanical Computers RN
navypedia.org
en.wikipedia.org
iwm.org.uk

Model Kits

smmlonline.com/reviews
O class DDs
modelwarships.com

3D