Commerce Raiders

By the summer of 1942 American submarines were conducting
"empire patrols" in Japan's coastal waters. USS Guardfish arrived
off Honshu in August 1942 and found thick merchant marine traffic.
On the afternoon of August 24, Guardfish sank the 3,100 ton
freighter Seikai Maru as it left Kinkasan Harbor. Traveling
north, Guardfish sank the 2,300 ton freighter Teikyu Maru
before turning south for another sweep. Moving very close to
shore Guardfish sank Tenyu Maru and Kaimei Maru on
September 4th. The submarine finished off the day with an
extraordinary torpedo shot that traveled over four miles
into a harbor to sink the 2,300 ton freighter Chita Maru.

During 1942, American submarines sank 179
Japanese ships.