The IJN used several ships captured from the British, Dutch and Americans as convoy escorts. These weren't captured in the traditional sense - they were never boarded. Instead, they were scuttled in port by their former owners when capture of the port seemed likely. The Japanese would later salvage them, and press them into service against their former owners.

The RN lost two ships in this way. HMS Thracian was on station at Hong Kong in December 1941. She remained at Hong Kong to provide fire support to the garrison, while the remainder of her squadron left for Singapore. She was scuttled after being heavily damaged by Japanese aircraft. She would be refloated in July 1942, and operated as patrol boat PB-101. She was recaptured in Yokosuka in 1945, and scrapped in 1946. The river gunboat HMS Moth would also be captured at Hong Kong, and operated on inland waterways in Japanese-occupied China.

The USN lost six ships in this way. USS Stewart, a Clemson class destroyer, fled the Philippines, and operated with ABDA forces in Indonesia. Heavily damaged after the Battle of the Bandung Strait, she was put into a floating drydock in Surabaya. She was not repaired before Java fell, and the drydock was scuttled with her inside. She was raised in 1943, and put back into service as PB-102. She would also be recaptured at the end of the war, and sunk as a target in 1946. The minesweeper USS Finch, fleet tug USS Genesse and Philippine customs vessel Arayat would be captured in Manila in various states of repair. They would enter Japanese service as PB-103, PB-107 and PB-105 respectively. Two gunboats, the USS Wake and USS Luzon were also captured, and put into service as the gunboats Tatara and Karatsu. Tatara fulfilled a similar role to the ex-HMS Moth, while Karatsu operated in the Philippines. PB-107 was destroyed by American carrier aircraft in Manila Bay at the start of November 1944, while PB-105 would be sunk by PT boats at the end of the month while escorting a convoy near Leyte. USS Finch would be sunk by aircraft from TF-38 while escorting a convoy off Vietnam in January 1945. Four Dutch ships were also captured, including one destroyer and three patrol boats. Another ship, the minesweeper Regulus, would be captured while under construction.

While purpose built warships were repurposed, in some cases merchant ships could be reused. The first escort carrier was built by the RN on the hull of a merchant ship captured from the Germans. The banana carrier Hannover was captured in the Caribbean in 1939. She was operated by the Merchant Navy until January 1941, when she was selected to become an escort carrier. She was the first to enter service, being commissioned in June 1941. She was renamed HMS Audacity in service. Audacity would operate with the RN for 6 months, escorting convoys to Gibraltar. Her fighters claimed 7 German aircraft before she was sunk escorting convoy HG76 by U-751.

Sources: Tabulated Records of Movement for the Japanese Navy, available at combinedfleet.com - look under the sections for escorts and gunboats.

The Fleet Air Arm Handbook 1939-1945, David Wragg, 2003, Sutton Publishing.