The S-class submarines were designed to patrol the restricted waters of the North Sea and the Mediterranean Sea. The third batch was slightly enlarged and improved over the preceding second batch of the S class. The submarines had a length of 217feet overall, a beam of 23feet and a draught of 14feet. They displaced 865LT on the surface and 990LT submerged.[1] The S-class submarines had a crew of 48 officers and ratings. They had a diving depth of 300feet.[2]
For surface running, the boats were powered by two 9500NaN0 diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 650hp electric motor. They could reach 15kn on the surface and underwater.[3] On the surface, the third batch boats had a range of 6000nmi at and 120nmi at submerged.[2]
The boats were armed with seven 21-inch (533 mm) torpedo tubes. A half-dozen of these were in the bow, and one external tube was mounted in the stern. They carried six reload torpedoes for the bow tubes for a grand total of thirteen torpedoes. Twelve mines could be carried in lieu of the internally stowed torpedoes. They were also armed with a 3-inch (76 mm) deck gun.[4] It is uncertain if Stratagem was completed with a 20mm Oerlikon light AA gun or had one added later. The third-batch S-class boats were fitted with either a Type 129AR or 138 ASDIC system and a Type 291 or 291W early-warning radar.[5]
HMS Stratagem was a third-group S-class submarine and was ordered as part of the 1941 Naval Programme on 3 August 1941. She was laid down in the Cammell Laird shipyard in Birkenhead on 15 April 1942 and launched on 21 June 1943.[6] On 24 September 1943, Stratagem sailed to Holy Loch, where she was commissioned into the Royal Navy on 9 October.[6] [7] Stratagem has so far been the only Royal Navy ship with this name.[8]
After training in several port areas, the boat departed Lerwick for a work-up patrol off Norway on 3 January 1944. She returned less than two weeks later without having sighted any enemy ships.[7]
Stratagem then had her battery changed at Sheerness on 23 January. The boat conducted additional training exercises until 3 March, when she was sent south to Gibraltar, and arrived on 14 April. The submarine was now commanded by Lt. C. R. Pelly. Along with and, Stratagem sailed to Malta in convoy USG 38 and then continued independently to Port Said before transiting the Suez Canal with a stop at Aden and finally arriving at Trincomalee, Ceylon, on 27 May.[7]
Stratagems first war patrol in the Far East started on 27 June 1944, when she departed Trincomalee to operate off the Andaman Islands. On 1 July, she fired four torpedoes at a Japanese merchant ship off Port Blair, but missed. On 2 July, she again unsuccessfully attacked another Japanese ship, as none of her six torpedoes hit their target. Two days later, the boat attacked the same merchant with her two remaining torpedoes and claimed a hit, but Japanese records do not mention a loss on this date. Having expended all her torpedoes, the submarine returned to port on 7 July.[7]
On 31 July, Stratagem departed Trincomalee for another patrol west of Siam. She returned to port on 22 August without having sighted any potential targets. From 16 September to 5 October, the boat conducted another patrol in the same area but only shelled warehouses and buildings on Great Coco Island and did not attack enemy ships.[7]
Stratagem departed Trincomalee for the last time on 10 November 1944, with orders to patrol in the Strait of Malacca. Nine days later, she torpedoed and sank the Japanese tanker Nichinan Maru in the Strait, the only victory in her career. On 22 November 1944, the submarine was detected by aircraft and attacked with depth charges by the Japanese submarine chaser CH 35. The first depth charge caused Stratagems bow to hit the sea bottom and caused flooding. The forward watertight bulkhead could not be closed, and she was forced to surface. The submarine was scuttled, and ten of her crew were taken prisoner, of whom only three survived the war.[7] [9]
During her service with the Royal Navy, Stratagem sank one Japanese ship of .[7]
| - | Date | Name of ship | Tonnage | Nationality | Fate and location |
|---|---|---|---|---|---|
| 19 November 1944 | Nichinan Maru | 1,945 | Torpedoed and sunk at |