Postwar research revealed the sunken boat to be , Commander Kudo Kaneo, that had sailed from the Inland Sea on 4 October 1944, to disrupt American shipping between the west coast and the Hawaiian Islands. In sinking "I-12", "Ardent" and "Rockford" avenged the atrocity "I-12" had committed on 30 October, when, after sinking the freighter "John A. Johnson" with two torpedoes, the submarine had rammed and sunk the lifeboats and rafts and then employed machine guns and pistols on the 70 survivors. Among the ten men slain were five sailors of the merchantman's US Navy Armed Guard. There were no survivors from "I-12"s 114 officers and men.