The flotilla was initially used in anti-submarine patrols around Guadalcanal's Cape Esperance. On 14 January 1943 Kiwi was the subject of a friendly fire incident when in poor light an American PT boat fired two torpedoes at her which only just missed. Bridson subsequently became friends with the commander of the PT boat. Later the same month, in the late evening of 29 January, Kiwi and Moa was carrying out patrols around Guadalcanal with Bridson in overall command. A Japanese submarine, the I-1, was detected by Kiwi, which launched a series of depth charges. The I-1 surfaced so it could use its 5-inch gun on the much smaller minesweepers. The Kiwi repeatedly rammed the submarine while firing point blank with its own 4-inch gun and an unofficial 20-mm Oerlikon that had been installed on its bow while stationed at Noumea. The submarine was badly damaged but broke free. Eventually, chased by Moa, the I-1 was stranded and sank on a reef. During this action, three of the Kiwi's crew were wounded, one fatally.
