The year 2000 marks the centennial of the U.S. Submarine Force. Among the most extraordinary accomplishments of American submariners is the impressive victory of U.S. World War II Fleet Boats over the Japanese Navy and Merchant Marine. While many books have been written describing this victory, few understand to what degree the U.S. Submarine Force gutted Japanese industrial and military strength during the Second World War. Such details are contained in the post war U.S. Strategic Bombing Study of Japanese industry and in Mark Parillo's excellent Japanese Merchant Marine in World War II.

The U.S. Pacific Submarine campaign had three major accomplishments. First, Japanese merchant marine losses crippled the ability of Japanese industry to generate military power. Second, destruction of Japanese merchant marine and naval forces significantly reduced the Japanese ability to project power throughout the vast Pacific. Third, use of the submarine enabled the U.S. Navy to take the offensive in Japanese controlled waters and inflict disproportionate losses relative to the U.S. investment in submarines.
 
We will review the effects of the U.S. submarine campaign on Japan including the effects on the four military pillars of Japanese power: her merchant marine, Navy, Army and air power. The implication for today's military, heavily dependent on logistics for power projection should not be forgotten. Today, even with the impressive and growing ability of the U.S. Navy to affect land warfare, sea control still remains job number one.

The Japanese attack on Pearl Harbor resulted in a significant loss of strength for the U.S. Navy and placed that Navy in a defensive posture. The only weapon system immediately available to take the war to the enemy was the U.S. Submarine Force. Indeed, FDR had decided prior to the start of the war that "unrestricted submarine warfare" would be undertaken in the event of hostilities with Japan. Throughout the war, the growing U.S. submarine force was employed in attacks on Japanese merchant shipping as well as on Japanese fleet units when the opportunity presented itself. In both these tasks, the American submarine force was aided by magic- intelligence derived from broken Japanese codes. The Japanese Navy, with Mahanian intellectual roots, prepared tardily and insufficiently for an onslaught not directly related to "decisive battle." The American Navy won a spectacular victory.

The Japanese Merchant Marine lost 8.1 million tons of vessels during the war, with submarines accounting for 4.9 million tons (60%) of the losses. Additionally, U.S. submarines sank 700,000 tons of naval ships (about 30% of the total lost) including 8 aircraft carriers, 1 battleship and 11 cruisers. Of the total 288 U.S. submarines deployed throughout the war (including those stationed in the Atlantic), 52 submarines were lost with 48 destroyed in the war zones of the Pacific. American submariners, who comprised only 1.6% of the Navy, suffered the highest loss rate in the U.S. Armed Forces, with 22% killed.

The American Pacific submarine campaign had substantial direct, indirect and second- order effects on the Japanese economy and the four bases of Japanese military power- Japanese airpower, the Army, the Imperial Japanese Navy and the merchant marine.