Were our submarines successful during the war?

Our submarines were very successful by the end of the war. They comprised only three percent of our Navy, yet they sank 55% of all the Japanese shipping sunk during the war. By the end of the war, Japan was nearly starved of fuel and short of food and many other supplies.

However, the war didn’t start out that way. There were many issues with submarines that limited our effectiveness. Some of these were specific to submarines and others applied to the Navy in general.