The Battle of Aachen was a major conflict of World War II, fought by American and German forces in and around Aachen, Germany, between 2–21 October 1944. The city had been incorporated into the Siegfried Line, the main defensive network on Germany's western border; the Allies had hoped to capture it quickly and advance into the industrialized Ruhr Basin. Although most of Aachen's civilian population was evacuated before the battle began, much of the city was destroyed and both sides suffered heavy losses. It was one of the largest urban battles fought by U.S. forces in World War II, and the first city on German soil to be captured by the Allies. The battle ended with a German surrender, but their tenacious defense significantly disrupted Allied plans for the advance into Germany.
By September 1944, the Western Allies had reached Germany's western border, which was protected by the extensive Siegfried Line. On 17 September, British, American, and Polish forces launched Operation Market Garden, an ambitious attempt to bypass the Siegfried Line by crossing the Lower Rhine River in the Netherlands. The failure of this operation, and an acute supply problem brought about by the long distances involved in the rapid drive through France, brought an end to the headlong Allied race toward Berlin. German casualties in France had been high - Field Marshal Walter Model estimated that his 74 divisions had the actual strength of just 25  - but the Western Allies' logistical problems gave the Germans a respite, which they used to begin rebuilding their strength. In September, the Wehrmacht high command's reinforcement of the Siegfried Line brought total troop strength up to an estimated 230,000 soldiers, including 100,000 fresh personnel. At the start of the month, the Germans had had about 100 tanks in the West; by the end, they had roughly 500. As men and equipment continued to flow into the Siegfried Line they were able to establish an average defensive depth of 3.0 miles (4.8 km).
Supreme Headquarters Allied Expeditionary Force (SHAEF), under the command of General Dwight D. Eisenhower, set their sights on the occupation of the Ruhr, Germany's industrial heartland. General George S. Patton's Third Army was given the task of occupying the French region of Lorraine, while General Courtney Hodges's First Army was ordered to break through the front near Aachen. Hodges had initially hoped to bypass the city itself, believing it to be held only by a small garrison, which would presumably surrender once isolated.
The ancient, picturesque city of Aachen had little military value in itself, as it was not a major center of war production. Its population of around 165,000 had not been subject to heavy bombing by the Allies. It was, however, an important symbol to both the Nazi regime and the German people; not only was it the first German city threatened by an enemy during World War II, it was also the historic capital of Charlemagne, founder of the "First Reich". As such, it was of immense psychological value. The mindset of the city's defenders was further altered by the different attitude the local population had toward them as they fought on home soil for the first time; one German officer commented, "Suddenly we were no longer the Nazis, we were German soldiers."
Aachen and its sector of the front were protected by the Siegfried Line, consisting of several belts of inter-connected pillboxes, forts, and bunkers protected by extensive minefields, "dragon's teeth" anti-tank obstacles, and barbed wire entanglements. In several areas, German defenses were over 10 miles (16 km) deep. It was, in the words of historian Stephen Ambrose, "undoubtedly the most formidable man-made defense ever contrived." Learning from their experiences on the Eastern Front, the Germans ran their main line of resistance down the center of towns located in the defensive wall, taking advantage of narrow streets to limit the mobility of enemy armored vehicles. Despite the low quality of many of the troops manning them, the fortifications protecting Aachen and the Ruhr were a formidable obstacle to the progress of American forces, who saw a breakthrough in this sector as crucial, as the terrain behind Aachen was generally flat, and therefore highly favorable to the motorized Allied armies.
Fighting around Aachen began as early as the second week of September, in a period known to the Germans as the "First Battle of Aachen". At this time, the city was defended by the 116th Panzer Division, under the command of General Gerhard von Schwerin.
The proximity of Allied forces had caused the majority of the city's government officials to flee before the evacuation of its citizens was complete. (For this, Hitler had all Nazi officials who had fled stripped of rank and sent to the Eastern front as privates.) Instead of continuing the evacuation, von Schwerin opted to surrender the city to Allied forces; however, on 13 September, before he could deliver a letter of capitulation he had written, von Schwerin was ordered to launch a counterattack against American forces penetrating southwest of Aachen, which he did, using elements of his panzergrenadier forces.
The German general's attempt to surrender the city would soon become irrelevant, as his letter was never delivered; instead, it fell into the hands of Adolf Hitler, who ordered the general's immediate arrest. He was replaced by General Gerhard Wilck. The United States' VII Corps continued to probe German defenses, despite the resistance encountered on 12–13 September. Between 14–16 September the US 1st Infantry Division continued its advance in the face of strong defenses and repeated counterattacks, ultimately creating a half-moon arc around the city. This slow advance came to a halt in late September, due to the supply problem, and the diversion of existing stocks of fuel and ammunition for Operation Market Garden in the Netherlands.
The Battle of Aachen had cost both the Americans and Germans dearly; the former suffered over 5,000 casualties, while the latter lost over 5,000 casualties and 5,600 taken prisoner. Since 2 October 1944, the 30th Infantry Division suffered roughly 3,000 men killed and wounded, while the 1st Infantry Division took at least 1,350 casualties (150 killed and 1,200 wounded).
The Germans lost another 5,100 casualties during the fighting in Aachen itself, including 3,473 prisoners. In the process of the battle, the Wehrmacht lost two complete divisions and had another eight severely depleted, including three fresh infantry divisions and a single refitted armored division; this was largely attributed to how they fought, as although an equivalent of 20 infantry battalions had been used during various counterattacks against the 30th Infantry Division alone, on average each separate attack only involved two infantry regiments.
During the conflict, the Germans also developed a respect for the fighting ability of American forces, noting their capability to fire indiscriminately with overwhelming amounts of artillery fire support and armored forces. Both the 30th Infantry and 1st Infantry divisions received distinguished unit citations for their actions at Aachen.
However, German resistance in Aachen upset Allied plans to continue their eastward advance. Following the end of fighting in Aachen, the Western Allies' First Army was tasked with the capture of a series of dams behind the Hürtgen Forest, which could be used by the Germans to flood the valleys which opened the road to Berlin. This would lead to the Battle of Hürtgen Forest, which was to prove more difficult than the Battle of Aachen.