The Ardennes Offensive (16 December 1944 – 25 January 1945) was a major German offensive launched towards the end of World War II through the forested Ardennes Mountains region of Belgium, France and Luxembourg on the Western Front. The offensive was called Unternehmen Wacht am Rhein (Translated as Operation The Guard on the Rhine or Operation "Watch on the Rhine.") by the German armed forces (Wehrmacht). This German offensive was officially named the Battle of the Ardennes by the U.S. Army, but it is known to the general public simply as the Battle of the Bulge. The “bulge” was the initial incursion the Germans put into the Allies’ line of advance, as seen in maps presented in contemporary newspapers. This offensive has several other names, including the Von Rundstedt Offensive (in reality, von Rundstedt had little to do with it) and, officially to the U.S. Army, the Ardennes–Alsace Campaign. Several historical works (notably David Eggenberger’s Encyclopedia of Battles) describe this battle as the Second Battle of the Ardennes.

The German offensive was supported by subordinate operations known as Unternehmen Bodenplatte, Unternehmen Greif, and Unternehmen Währung. Germany’s planned goal for these operations was to split the British and American Allied line in half, capturing Antwerp, Belgium, and then proceeding to encircle and destroy four Allied armies, forcing the Western Allies to negotiate a peace treaty in the Axis Powers’ favour. Battle of the Bulge

The Germans planned the offensive with utmost secrecy, minimizing radio traffic and conducting the movement of troops and equipment under cover of darkness. Although ULTRA, the Allies’ reading of secret German radio messages, suggested a possible German offensive, and the United States Third Army predicted a major German offensive, the attack still achieved surprise. The degree of surprise achieved was compounded by the Allies’ overconfidence, their preoccupation with their own offensive plans, poor aerial reconnaissance, and the relative lack of combat contact in the area by the U.S. 1st Army. Almost complete surprise against a weak section of the Allies’ line was achieved during heavy overcast weather, when the Allies’ strong air forces would be grounded.

For the U.S. Army, the battle incorporated more troops and engaged more enemy troops than any conflict before that time. The German objectives ultimately were unrealized. In the wake of the defeat, many experienced German units were left severely depleted of men and equipment, as German survivors retreated to the defences of the Siegfried Line. The Battle of the Bulge was the bloodiest of the battles that U.S. forces experienced in World War II; the 19,000 American dead were unsurpassed by those of any other engagement