What role did US submarines play in World War 2?
US subs served mainly in the pacific, operations in the Atlantic were minimal.
US subs did to Japan what German subs wanted to do to Britain. Wipe out merchant navy!
After a bad start �magnetic detonators didn�t work at all, mechanic detonators hardly worked and the torpedoes ran several feet deeper than they should- US subs sank 201 warships and close to 1100 merchant ships, reducing the Japanese merchant navy from 6 million grt to 1.8 million. What was left were mainly small wooden ships sailing in coastal waters.
Japan cared very little about protecting their merchant ships. Organisation and technology to fight submarines were just a joke and contributed a lot to the US success.
US subs projected power to Japan as no other sea vessel ever did. Sending millions of tons of greatley needed Japanese war supplies to the bottom turned the tide of the war for America. Japan could not build ships faster than we could sink them and was literally threadbare and choked off of supplies at the end of the war. Submarines have long been underrated in their ww2 contribution. Truly the sub fleet of the Pacific won the war against Japan.
Not to repeat, it could be argued that the Submarine force won the war in the Pacific. In fairness, however, had Japan not had the island hopping campaigns of Nimitz and MacArthur to deal with, it is unlikely the sub force would have been as effective. In short, the multi-faceted Army-Navy-Marine Corps battles, along with the relentless attacks by the U.S. Submarine Force, won the war.
In terms of efficiency, however, the submarine force destroyed 90% of the merchant fleet with which Japan started with war and also destroyed one-third of the Imperial Japanese Fleet. This while at no time did the submarine force comprise more than 2% of the Navy's men and materiel.
And the sub force started the war with virtually no effective submarine tactics (the Navy had spent the previous ten years trying to develop a submarine to operate with the surface fleet, primarily as scouts) and the infamous Mark 10 torpedo and Mark 14 magnetic exploder. It took nearly three years and the loss of many men and many careers before the Bureau of Ordnance was finally convinced of its folly. Had Admiral Lockwood not been willing to put his own career on the line, there might never have been a reliable working torpedo in WWII. And even after fixing the Mark 10, they (Bureau of Ordnance) did not listen to the sub captains, and as a result at least two U.S. submarines were sunk by their own malfunctioning Mark 18 electric torpedoes (read "Clear the Bridge! War Patrols of the USS Tang").
Politics and bureaucracy do not take vacation during war. They remain with their promises and their paperwork, respectively, doing good for themselves and everyone else be damned.