- Theatre: North West Europe
- Dates: 16 December 1944 to 23 January 1945
- Location: Belgium and Luxembourg
- Outcome: An abortive offensive, weakening and diverting German forces. The battle was fought in extreme conditions: winter storms and snow limited air support and hindered ground operations.
- Allies: Field Marshal Bernard Montgomery's 21st Army Group comprising General Miles Dempsey's 2nd Army (including 30th Corps) and Lieutenant General Henry Crerar's Canadian 1st Army; General Omar Bradley's US 12th Army Group comprising Lieutenant General Courtney Hodges' US 1st Army, General George Patton's US 3rd Army and Lieutenant General William Simpson's 9th Army
- Axis: Field Marshal Walter Model's Army Group B, including General Hasso Eccard von Manteuffel's 5th Panzer Army, SS General Josef Dietrich's 6th Panzer Army and General Erich Brandenberger's 7th Army
The Allied front in southern Belgium and eastern France was composed of two American armies: General Courtney Hodges' 1st Army and General George Patton's 3rd Army. Hitler's last attempt to turn the tide of the war, the Ardennes offensive, focused on the area between these two armies.
Flanked by the 7th Army to the south, the 5th and 6th Panzer Armies were to break through the American line and advance to the Meuse. The 5th Panzer Army would then make for Brussels and the 6th for Antwerp, encircling and destroying the American, British and Canadian forces to the north of this double advance - Hodges' 1st Army and the whole of Montgomery's 21st Army Group.
Like many of Hitler's personal military interventions in the latter half of the war, the planned offensive was bold, imaginative and completely unrealistic; even Field Marshal Walter Model, commander of Army Group B, objected to the plan, arguing that objectives west of the Meuse were unattainable.
Initially, however, the offensive had considerable success. Throwing three armies against a point in the Allied line guarded by four American divisions, within five days Model had pushed the American line back by 80km (50 miles), creating a 'bulge' in the line. As well as giving the Allies a nightmarish reminder of the German skills in blitzkrieg tactics, the advance cut communications between Bradley, south of the bulge, and Hodges and Simpson to the north.
Eisenhower therefore transferred both armies temporarily to Montgomery's 21st Army Group. Adopting his characteristic approach of drawing the enemy onto his own territory, Montgomery stationed 30th Corps units along the Meuse, which had been Model's first day's objective; as it turned out, no German unit got within 8km (five miles) of the river.
The offensive was over almost as soon as it had begun. Many units were overrun and a few fled in panic, but most of the American forces resisted the attack promptly and tenaciously enough to bring it to a halt within days. The strategically important town of Bastogne, garrisoned by the US 101st Airborne Division, was completely surrounded but never fell; the 101st acting commander, Brigadier General Anthony McAuliffe, famously replied to a formal surrender request with one word: 'Nuts!' Patton's Third Army, advancing from the south, relieved Bastogne on 26 December. Manteuffel asked Hitler's permission to withdraw and prepare for the inevitable counter-attack. Hitler replied by ordering his armies to remain in the Ardennes salient - and to take Bastogne.
Bradley launched a counter-attack from the south on 30 December; three days later Montgomery attacked from the north and north west, deploying the US 1st Army together with 30th Corps. Despite adverse weather conditions, the two forces steadily closed the gap, meeting on 13 January 1945. Ten days later the Americans retook St Vith, 8km (five miles) from the German starting line. The Ardennes offensive had been broken, at a cost to the Germans of 120,000 men.