The 1st Airborne Division was an airborne infantry division of the British Army during the Second World War. The division was formed in late 1941 during the Second World War, after the British Prime Minister, Winston Churchill, demanded an airborne force, and was initially under command of Major-General Frederick A. M. Browning. The division was one of two airborne divisions raised by the British Army during the war, with the other being the 6th Airborne Division, created in May 1943, using former units of the 1st Airborne Division.

The division's first two missions—Operation Biting, a parachute landing in France, and Operation Freshman, a glider mission in Norway—were both raids. Part of the division was sent to North Africa at the end of 1942, where it fought in the Tunisian Campaign, and when the Allies invaded Sicily in July 1943, the division undertook two brigade sized landings. The first, Operation Ladbroke, carried out by glider infantry of the 1st Airlanding Brigade and the second, Operation Fustian, by the 1st Parachute Brigade, were far from completely successful. The 1st Airborne Division then took part in a mostly diversionary amphibious landing, codenamed Operation Slapstick, as part of the Allied invasion of Italy in September 1943.

In December, most of the 1st Airborne Division (minus the 2nd Parachute Brigade) returned to England, and began training and preparing for the Allied invasion of Normandy. It was not involved in the Normandy landings in June 1944, being held in reserve. In September 1944 the 1st Airborne took part in Operation Market Garden. The division, with the Polish 1st Parachute Brigade temporarily attached, landed 60 miles (97 km) behind German lines, to capture crossings on the River Rhine, and fought in the Battle of Arnhem. After failing to achieve its objectives, the division was surrounded and took very heavy casualties, but held out for nine days before the survivors were evacuated.

The remnants of the 1st Airborne Division was returned to England soon after. The division never fully recovered from their losses at Arnhem and the 4th Parachute Brigade was disbanded. Just after the end of the war in Europe, the depleted formation took part in Operation Doomsday in Norway in May 1945. They were tasked with the disarmament and repatriation of the German occupation army. The 1st Airborne Division then returned to England and was disbanded in November 1945.