The Japanese lost 1,178 Merchant Ships sunk for a tonnage total of 5,053,491 tons. The Naval losses were 214 ships and submarines totaling 577,626 tons. A staggering five million, six hundred thirty one thousand, one hundred seventeen tons, (5,631,117 tons), 1,392 ships.

Japan ended the war with a bare 12% of her merchant fleet intact but not fuel at hand to run more than a few of them.

Action in the Atlantic showed far fewer successes, mainly due to poor torpedo performance. By May of 1943 US submarine involvement had almost ceased in the Atlantic except for training and sea trials of new subs. US submarine losses in the Atlantic were few and may have been the result of an aggressive anti-submarine program by US and allied powers.

The U.S. Navy lost 52 submarines sunk and 4023 men of the submarine service died while on boats. These boats and crews left port and never returned. Their final resting place, and the circumstances surrounding their fate is, for the most part, unknown. We, in the Submarine Service, refer to these boats and men as being on  Eternal Patrol

This page is not about the losses of our submarines but about the aggressive pursuit of enemy shipping and commerce conducted by these same submarines.

After the attack on Pearl Harbor where the greater part of the U.S. capital fleet had been damaged or destroyed, the only means of carrying the war to the Japanese was our submarines. Only five boats had been in port and the sub base was untouched in the attack.  A submarine, the USS TAUTOG, it's .50 caliber machine gun, manned by Torpedoman's Mate Pasqual "Pat" Mignon, opened fire on a flight of torpedo bombers and shot one down unassisted. The first confirmed enemy causality by a submarine was an airplane. Other crews, along with fire from the various ships helped bring down several other planes. Six boats were in port on the west coast having work done or doing training exercises.  The rest were either out on patrol or were in transit to Pearl Harbor when the attack happened.

On the afternoon of December 7, 1941 the order was issued by the Chief of Naval Operations to:

"EXECUTE UNRESTRICTED AIR AND SUBMARINE WARFARE AGAINST JAPAN"

After the war the Joint Army-Navy Assessment Committee went through all the Japanese and American records and sought out confirmation of sinkings. This has raised some dispute in Submarine circles since their logbooks show sinkings and tonnage that can not be confirmed by independent sources. Over estimating tonnage was common but not done on purpose. It is tough to guess if a ship is 9000 tons or 6000 tons from 1500 yards and an elevation of 6 inches above the water in the middle of the night while the enemy is trying to sink you. Sometime subs needed to take evasive action before seeing the ship sink. It might have been towed to safety and salvaged or managed to get back underway and leave the area of the sub.
The following pages reflect the "official" sinkings approved by JANAC and "unofficial" hits, sinkings and damage assessments to enemy ships from SORG's (Submarine Operation Research Group) compilation of submarine attacks at the end of the war. Many ships reported sinkings but these were not confirmable from Japanese records so JANAC does not include them. Also ships sunk or damaged by several subs or combinations of submarine and aircraft or ship are not reported by JANAC. Likewise if a ship was less than 500 tons burden it wasn't included in the JANAC total.
Many times a ship was torpedoed and the crew ran it up on a beach. It didn't "sink" but you can still see the hulks today. JANAC doesn't credit those either even though the ship was out of the war as effectively as if it had been sunk.