The first USS Oahu (PR-6), a Yangtze River gunboat, was laid down by Kiangnan Dock and Engineering Works, Shanghai, China, 18 December 1926; launched as PG–46 on 26 November 1927; sponsored by Mrs. Bryson Bruce, wife of Comdr.

Beginning in 1934, Oahu took up duty as station ship at various Yangtze ports supplying the increasing river traffic with naval armed guard detachments on a regular basis.

Following the sinking of sister gunboat Panay off Nanjing by Japanese planes 12 December 1937, Oahu picked up the survivors and carried them to Shanghai, returning to the scene of the incident to conduct salvage operations.

As the Japanese campaign in China grew, the gunboat operated only on the lower river as far as Wuhu and Hankou, in addition serving as station ship and radio relay vessel for American officials at the temporary U.S. embassy at Nanjing.

Oahu remained as station ship at ports below Hankou, returning to the latter city to refit and give liberty to her crew until late in November 1941 and then, under orders of Commander, Asiatic Fleet departed Shanghai for the Philippines as signs of approaching war with Japan became clearer.