In 1944, the German 1st Army of Army Group G under General Otto von Knobelsdorff occupied the Maginot line in face of the US advance. However the Maginot line was of limited use to the defending Germans for a number of reasons. Firstly the Maginot line was designed to withstand an Eastern assault, not Western, meaning all of the gun emplacements and bunkers were facing the wrong way. Secondly, following France's capitulation the pockets of French resistance still occupying the Maginot line were surrounded and destroyed. Many of the heavy guns and bunkers were destroyed, and no effort was made to restore them. The only real use the Maginot line had to offer the defending Germans was an underground area to sleep. Furthermore, mobile defence with harsh counter attacks instead of static defence was favoured by the German high command, so they had no real intention of using the Maginot Line to its full potential. In short, many of the fortifications of the Maginot line were easily captured by the allied forces in the west because they were ill maintained and in some cases, empty. However there are a few cases in which the German defenders used the forts of the Maginot line to their full potential and proved extremely difficult for the US army to deal with. Their defence was fairly irrelevant in the grand scheme of the war however, as they were mostly bypassed by the advancing Americans.

The Siegfried line or 'Westwall' was a far less formidable defensive line when compared to the Maginot line. When inspecting the Siegfried line, Field Marshal Gerd Von Rundstedt supposedly laughed at its weak construction and insufficient armament. Not much effort was dedicated to reinforcing the Siegfried line as the German high command expected the war with France and Britain to end relatively quickly and painlessly, and certainly did not anticipate an American invasion. Following the Normany landings on the 6th of June 1944, Hitler ordered 20,000 labourers (aged 14 - 16) of the Reichsarbeitsdeinst to begin renewing the defensive line. The poorly built structures of the Siegfried line fell victim to improved armour piercing weaponry, which meant the vast majority of the line fell with no significant setbacks. The battle of Hurtgen Forrest was perhaps one of the most notable defensive battles fought by the Wehrmacht on the Siegfried line; and also the longest fought battle by the US army. The German occupants refused to surrender to American forces until February 1945, having been defending since September 1944. The defence was again however futile, as they were bypassed by the majority of the US army. The Battle of the Bulge fought in the Ardennes Forrest displays the German high command's higher regard of mobile defensive over static. The battle of the Bulge was the last major offensive fought by the Wehrmacht. A large number of infantry, assault guns, and tanks attacked a bulge in the American line, which caught Allied Supreme command completely off guard, thanks to the complete secrecy of the Germans. The offensive saw some initial success but the heavy losses on both sides favoured the allies, as the Germans were in dire need of manpower. The assault ended in a disastrous defeat for the defending Germans, effectively causing the defence of the Siegfried line to collapse.