U-boat Threat to U.S.
Among the strategies for dealing with the U-boat threat to U.S. shipping was a series of small vessels, designed to be built cheaply and quickly, and optimized to find and hunt submarines. The sub chasers were small, but ended up playing out-sized roles along the coasts of the United States and around the world. The History Guy tells the forgotten story of the submarine chasers of the U.S. Navy.
Credit to : The History Guy: History Deserves to Be Remembered