 Still in Shanghai at the beginning of the Pacific War on 8 December 1941 , Izumo captured the American river gunboat USS Wake and assisted in sinking the British river gunboat HMS Peterel . On 31 December , the cruiser struck a mine in the Lingayen Gulf while supporting Japanese forces during the Philippines Campaign . During this period , Iwate was still serving as a training ship in home waters . The sisters were briefly re @-@ classified as 1st @-@ class cruisers on 1 July 1942 before they became training ships in 1943 . Izumo returned to Japan late that year and joined her sister in training naval cadets . 
