It Was What They Did (DBF)
During the 1,347 days of WWII, 465 skippers took 263 boats and 16,000 men out on 1,736 patrols, collectively spending 79,838 days at sea, of which 31,571 days were spent in operating areas where they attacked 4,114 merchant ships, firing 14,748 torpedoes and sinking 1,178 of them along with 214 Naval vessels. Of these 263 boats, 52 and 3,617 men never returned.
Never in the annals of military history has there been a record of achievement to equal that of the United States Submarine Service during WWII. With 1.6 percent of all Naval personnel, the Submarine Service sank over 55% of all Japanese ships sunk, including one-third of all Japanese Men-of-War.
They also performed many other tasks such as carrying ammunition to Corregidor, evacuating the Philippine government and all its gold, attacking enemy land positions, landing spotters and raiders on many islands, and rescuing downed U.S. pilots.
Secret surveillance was another mission of the submarines. U.S. submarines scouted every landing made during the war in the Pacific and on many occasions acted as “point” for the invading forces guiding them to the invasion place.
The United States Submarine Service had the Island of Japan isolated long before the end of the war. Japan was unable to support their army in the field, or even sustain the economy of the home islands.