The Battle of the Bulge in World War II happened because of Hitler's plan to launch a counter-offensive to thrust through the allied armies in the Ardennes region of northwest Europe and recapture Antwerp in Belgium. Because the allies were unprepared for the attack, the German offensive made considerable initial progress, creating a large bulge in the allied line.
The offensive, launched on December 16, 1944, was a desperate attempt by Hitler to salvage victory on the deteriorating western front. More than 250,000 German troops, aided by inclement weather and weakly-defended lines, drove deep into the forests of the Ardennes, overwhelming surprised American troops. Stiff allied resistance prolonged the battle, causing the Germans to run low on supplies and ammunition. The battle continued until January 25, 1945.
The Battle of the Bulge was the bloodiest and costliest battle of the war for the Americans. More than 100,000 of their troops were killed, wounded, captured or missing. However, in the end, the Germans were forced to withdraw due to lack of fuel, heavy resistance by the allies and the arrival of General George Patton's Third Army, which was diverted from Lorraine and sent to break through the German siege of the town of Bastogne. The battle sapped German reserves, decimating its air force. By early February, the bulge had been closed and the lines returned to their previous locations.