- 14-February-1943 : WWII: Battle of the Kasserine Pass: German General Erwin Rommel and his Afrika Korps launch an offensive against Allied defenses in Tunisia; it is the United States' first major battle defeat of the war.
- 27-February-1943 : The Smith Mine #3 in Bearcreek, Montana, United States explodes, killing 74 men.
- 02-March-1943 : WWII: Battle of the Bismarck Sea United States and Australian forces sink Japanese convoy ships.
- 13-March-1943 : WWII: On Bougainville, Japanese troops end their assault on American forces at Hill 700.
- 11-May-1943 : WWII: American troops invade Attu in the Aleutian Islands, in an attempt to expel occupying Japanese forces.
- 06-July-1943 : WWII: Americans and Japanese fight the Battle of Kula Gulf off Kolombangara.
- 24-July-1943 : WWII: Operation Gomorrah begins: British and Canadian aeroplanes bomb Hamburg by night, those of the Americans by day. By the end of the operation in November, 9,000 tons of explosives will have killed more than 30,000 people and destroyed 280,000 buildings.
- 06-August-1943 : WWII Battle of Vella Gulf: Americans defeat a Japanese convoy off Kolombangara, as the U.S. Army drives the Japanese out of Munda airfield on New Georgia.
- 05-September-1943 : WWII: The 503rd Parachute Regiment under American General Douglas MacArthur lands and occupies Nadzab, just east of the port city of Lae in northeastern Papua New Guinea.
- 01-October-1943 : WWII: American forces enter liberated Naples.