1917 - The U.S. Naval Armed Guard crew on board SS Mongolia engages and damages a German U-boat, the first engagement against the enemy after declaration of war on April 6.
1920 - The first German submarine brought to the United States after World War I arrives at New York. During World War I, U 111 sank three Allied merchant vessels that included the British steamer Boscastle on April 7, 1918. The submarine surrendered later that year.
1945 - USS Buckley (DE-51) and USS Reuben James (DE-153) sink the German submarine U-879 southeast of Halifax, Nova Scotia.
1955 - USS Albany (CA 123) and USS William Wood (DD 715) begin providing disaster relief to citizens of Volos, Greece, following a catastrophic earthquake.
1960 - the Grumman A2F-1 "Intruder" makes its first flight. The Intruder receives the designation of A-6A in 1962, and upon entering service in 1963, becomes the U.S. Navy and Marine Corps principle all weather/night attack aircraft.