On the afternoon of 10 June "Harder" sighted a large Japanese task force, including three battleships and four cruisers with screening destroyers. An overhead plane spotted the submarine at periscope depth and a screening escort promptly steamed at toward her position. Once again, "Harder" became the aggressive adversary. As the range closed to , she fired three torpedoes on a "down the throat" shot, then went deep to escape the onrushing destroyer and certain depth charge attack. Within a minute two torpedoes blasted the ship with violent force just as "Harder" passed her some below. The deafening explosions shook the submarine far worse than the depth charges and aerial bombs which the infuriated enemy dropped during the next two hours. When she surfaced, "Harder" saw only a lighted buoy marking the spot where the unidentified destroyer either sank or was heavily damaged.