September 3 in Military History

Oliver Cromwell, Lord Protector of the Commonwealth of England, Scotland, and Ireland, died at Whitehall Palace in London. The former commander of the New Model Army had commanded Parliamentary forces at Marston Moor, Naseby, and Dunbar, and presided over the only period of republican rule in British history. His death precipitated a political crisis that ended in the restoration of the monarchy two years later.

American and British forces clashed at Cooch's Bridge in Delaware during the Philadelphia Campaign. It is traditionally considered the first battle in which the Stars and Stripes was carried into combat, though this claim is debated by historians. The American light infantry under Brigadier General William Maxwell delayed but could not stop the British advance toward Philadelphia.

The Treaty of Paris was signed by representatives of King George III and the United States, officially ending the American Revolutionary War. Britain recognized American independence and ceded all territory east of the Mississippi River to the new nation. The treaty was negotiated by Benjamin Franklin, John Adams, and John Jay.

U.S. Army forces under Brevet Brigadier General William S. Harney attacked a Brulé Lakota village at Blue Water Creek in present-day Nebraska in retaliation for the Grattan Massacre of the previous year. The assault killed approximately 86 Lakota, including many women and children, and captured 70. The battle marked a significant escalation in the conflicts between the U.S. Army and the Lakota Sioux on the Great Plains.

Royal Flying Corps pilot Lieutenant William Leefe Robinson shot down the German Schutte-Lanz SL11 airship over Cuffley, north of London, using incendiary ammunition. It was the first German airship destroyed over British soil and earned Robinson the Victoria Cross. The victory broke the psychological hold of the Zeppelin campaign and validated the new incendiary rounds designed specifically for airship hunting.

Following Germany's invasion of Poland two days earlier, Great Britain and France declared war on Nazi Germany, transforming a regional conflict into a world war.

The German submarine U-30 torpedoed the British passenger liner SS Athenia in the North Atlantic, killing 112 of the 1,418 passengers and crew. The sinking, which occurred just hours after Britain's declaration of war, was the opening shot of the Battle of the Atlantic, the longest continuous campaign of World War II. Germany initially denied responsibility, fearing comparison to the Lusitania sinking of 1915.

British and Canadian forces of Montgomery's Eighth Army crossed the Strait of Messina and landed on the toe of mainland Italy in Operation Baytown, the first Allied invasion of Axis-controlled continental Europe. Italian resistance was minimal, as the Badoglio government had secretly signed an armistice five days earlier. The landing began the grueling Italian Campaign that would continue until May 1945.

North Korean forces launched a renewed offensive across the Naktong River against the US 2nd Infantry Division, attempting to break through to Pusan before the planned landing at Inchon. Four NKPA divisions crossed the river under cover of darkness, seizing multiple bridgeheads. The 2nd Division and attached Marine units fought a grinding two-week battle to eliminate the penetration, suffering heavy casualties but destroying the last offensive capability of the NKPA.

General Nguyen Van Thieu won South Vietnam's presidential election in a vote widely criticized as fraudulent. Thieu would rule South Vietnam until its final days in April 1975, overseeing the Vietnamization of the war and the eventual collapse of his government. His authoritarian leadership complicated American efforts to build a legitimate democratic alternative in South Vietnam.