May 11 in Military History

Mutinous sepoys from Meerut seized Delhi and proclaimed the Mughal Emperor as their leader, triggering the largest uprising against British colonial rule.

The Confederate ironclad CSS Virginia (formerly USS Merrimack), which had revolutionized naval warfare in her battle with USS Monitor two months earlier, was destroyed by her own crew when Norfolk was evacuated. The ship drew too much water to retreat up the James River, and the Confederacy could not allow her to fall into Union hands.

U.S. Army troops landed on Attu Island, Alaska, to retake it from Japanese forces who had occupied it since June 1942. The three-week battle in brutal Arctic conditions cost 549 Americans killed and saw one of only two banzai charges against U.S. forces in the war.

Allied forces launched their fourth and final assault on the German Gustav Line at Monte Cassino in Italy. The offensive, involving French, Polish, British, and American forces, finally broke through the German defenses after four months of bloody fighting.

Thailand and the United States signed follow-on military training arrangements that extended earlier postwar agreements, creating the foundation for a U.S.-Thai military partnership that would host thousands of aircraft during the Vietnam War.

Israel began mobilizing its reserve forces as tensions escalated with Egypt, Syria, and Jordan. Egyptian President Nasser had demanded the withdrawal of UN peacekeepers from Sinai and was massing troops on the border. The crisis would erupt into the Six-Day War on June 5.

U.S. 101st Airborne Division troopers, supported by ARVN paratroopers, continued the costly assault on Ap Bia Mountain (Hill 937) in the A Shau Valley, the engagement that would become known as Hamburger Hill.

The trial of Klaus Barbie, the "Butcher of Lyon," opened in France, 42 years after the end of World War II. Barbie, the former Gestapo chief in Lyon, was charged with crimes against humanity for the deportation of hundreds of Jews including 44 children from a home in Izieu. He was convicted and sentenced to life in prison.

U.S. Air Force combat aircraft completed Operation Vigilant Sentinel, a no-fly zone enforcement deployment over northern and southern Iraq that continued the post-Gulf War containment mission under Operations Northern Watch and Southern Watch.

IBM's Deep Blue chess computer defeated world champion Garry Kasparov in a six-game match, a milestone that accelerated Department of Defense interest in artificial intelligence for command and control, logistics planning, and decision support.