Operation Market Garden was a military operation for the Allied invasion of Germany through Holland, in the hopes of ending the war by the Christmas of 1944. The operation was the brainchild of British General Bernard Montgomery.
Three airborne divisions, two American, one British, and one Polish brigade were to capture key bridges on the road from Eindhoven, at Zon, Veghel, Grave, Nijmegen, and Arnhem. The two American divisions were the 82nd and 101st airborne divisions, the British contributed the 1st airborne division, and the Polish contributed the 1st airborne brigade.
After bombing from well over 1,000 bombers the invasion began with also over 1,000 troop transports supported by several hundred fighter escorts. Few casualties were sustained in the first day from either troop or aircraft. Paratroopers and gliders also had a very high rate of success in landing in their designated landing spots. After the initial victory of day one however, multiple factors began to turn the mission to failure. Obviously, after the initial surprise, the Germans defending the area reorganized and prepared for attack losing the element of surprise. Also communication was quite poor, making communication between fellow soldiers difficult; combined with the poor weather, calling in air or artillery support was near impossible. The poor weather also caused many reinforcements to be grounded, preventing them from assisting troops already on the ground.
More Info: Medical Operations during Market Garden
Total casualties are debated ranging from around 15,300 to 17,200 Allied troops and aproximentally 6,300 to 8,900 Germans. There was also reports of several hundred dead civilians being at around 500 people. It was the largest airborne battle in the history of warfare and lasted from September 17 to the 25th in the year 1944.