From 1920 to 1939, the company built various types of government and commercial vessels and private yachts, including three Coast Guard Cutters. In 1931, Defoe built the Lenore, a yacht for Montgomery Ward Chariman Sewell L. Avery, who named it after his second daughter that died at the age of four; this yacht was taken by the U.S. Government in World War II for coastal picket duty by the Coast Guard, and in 1956 it was assigned as a Presidential Yacht. It was called the Barbara Anne by President Eisenhower after his granddaughter, the Honey Fitz by President Kennedy in honor of his maternal grandfather John Francis Fitzgerald, and the Tricia by President Nixon after his daughter. In 1941, the name of the company was changed to Defoe Shipbuilding Company.
During World War II, all production went to the war effort. From 1939 to 1945, the company built 154 ships, including 4 minesweepers, 13 destroyer escorts, fast transports, patrol craft, and landing craft. Defoe developed a construction technique called the "upside-down and roll-over" method. This allowed most of the welding of the hull to be done "hand down" which is much easier. After the hull was completely welded, it was rolled over by a set of large wheels fastened to each end of the hull. Work then continued on the ship right-side up. Faster welding allowed the company to build one 173-foot PC, patrol craft, every week.
After World War II, the company built bulk carriers and did repair work on Great Lakes ships. In later years, several ships were built for the US Navy, including 2 Dealy class destroyer escorts, 4 Charles F. Adams class guided missile destroyers, 3 Garcia class destroyer escorts (later re-classified as frigates), and three guided-missile destroyers for the Australian Navy. Also built there were the research vessels R/V Melville and R/V Knorr, which was the ship that found the RMS Titanic.
The yard closed on 31 December 1976 after the Navy contracts ran out. The site of the shipyard later became the location for H. H. Hirschfield & Sons scrap yard. Hirschfield was recently bought out by OmniSource, Inc., another scrap company.