The E-class submarines were a class of two United States Navy submarines, built by the Fore River Shipbuilding Company of Quincy, Massachusetts, under a subcontract from the Electric Boat Company. They were used as coastal and harbor defense submarines prior to World War I. When hostilities broke out, the E class were mostly used as training boats; however, E-1 operated on war patrols based in the Azores. During this time, the need for an improved permanent bridge structure was discovered; the temporary piping-and-canvas bridges were inadequate in the North Atlantic.

The United States D-class submarines were a trio of submarines built for the United States Navy in the first decade of the 20th century. All three ships served during World War I providing training for crews and officers on the U.S. East Coast, before the class was decommissioned and sold for scrap in 1922.