The 'Siegfried-Linie' was the German major defence line in the west of Germany, essentially a counterpart to the French 'Ligne Maginot' but constructed to slightly more modern concepts with better anti-tank defences and less reliance on fixed fortifications mounting large-calibre guns (1940/45).

The line ran from Kleve on the Dutch/German border to the east of Nijmegen (where the Rhine river crosses into the Netherlands) and then to the south along the German frontier toward the town of Weil-am-Rhein on the German/Swiss frontier in the area just to the north-east of Basle. The 'Siegfried-Linie' was also known to the Germans as the 'Westwall', especially after it had been modified and developed from July 1944, following a period of neglect, as the major check to the Allies' eastward offensive toward Germany.

The 'Siegfried-Linie' was built during the 1930s opposite the French 'Ligne Maginot', and served essentially the same operational role. The Germans themselves called this the 'Westwall', but the Allies renamed it after the primary portion of the 'Hindenburg Line' defences built during 1916/17 as Germany’s most important protection against offensives from the west in World War I.

The 'Siegfried-Linie' was thus a defence system stretching more than 390 miles (630 km) and including more than 18,000 bunkers, tunnels and tank traps.

With propaganda rather than specifically military requirements in the forefront of his thinking, Adolf Hitler planned the line from 1936 and ordered its construction between 1938 and 1940. This was after the time the Nazi government of Germany had broken the terms of the Treaty of Versailles and Treaty of Locarno by remilitarising the Rhineland in 1936.

As initially completed in 1938/40, the 'Westwall' was built in several phases comprising the Grenzwach Programm(border watch) programme for the most advanced positions in 1938, the Limes Programm (Latin for frontier) in 1938, the Aachen-Saar Programm in 1939, the Geldern-Stellung between Brüggen and Kleve in 1939/40, and the Luftverteidigungszone 'West' Programm (western air-defence zone programme) in 1938. These programmes were implemented with the highest priority, using every resource available. Each programme began with the design and construction of a prototype, which on approval was then manufactured in large numbers as the structural core of the programme, which could then be identified by the standardisation of its bunkers and tank traps. This fact reflected not so much Germany’s belief in standardisation as such, but the country’s lack of the raw materials, transport and workers for the creation of more fully optimised structures reflecting the needs of any particular location.

In the Grenzwach Programm, small bunkers were set up with three embrasures facing toward the front. The walls were only 19.75 in (0.5 m) thick and provided no protection against gas attack. Soldiers stationed there did not have their own beds but had to make do with hammocks. In exposed positions, similar bunkers of very modest size were erected with small armoured look-out sections of circular section on their roofs. All these constructions were considered obsolescent even as they were built, and at best offered protection only against bomb, shell and grenade fragments. The programme was carried out by the Grenzwacht, which was a small military organisation activated in the Rhineland immediately after this region’s remilitarisation.

The Limes Programm began as a result of Hitler’s order for a strengthening of the defensive fortifications on Germany’s western frontier. The bunkers constructed in this programme were more robust than those of the Grenzwach Programme. The structure for each of this programme’s Type 10 bunkers probably required 20 man years to build, and required a volume of concrete similar to that needed for the building of a small block of apartments. The ceiling and walls of each bunker were 5 ft (1.5 m) thick, but this was proved completely insufficient even before construction was finished. Even so, some 3,470 such bunkers were built along the entire length of the 'Siegfried-Linie', each based on a central room or shelter for 10 to 12 men with an entrance, stepped embrasures facing backward and a combat section 19.75 in (0.5 m) higher. This section had embrasures at the front and sides for machine guns, and a separate entrance. More embrasures were provided for small arms and, as a result of German experience in World War I, the entire structure was protected against gas attack. The bunker was heated by a solid-fuel stove whose chimney, leading to the structure’s outer surface, was protected by a thick grating to prevent explosive charges from being dropped down it. Every soldier was given a sleeping place and a stool, and the senior man also had a chair. The bunker was comparatively small for its complement, and space was therefore at a premium.

The bunkers of the Aachen-Saar Programm were similar to those of the Limes Programm, but these Type 107 bunkers had double machine gun casemates with concrete walls up to 11 ft 6 in (3.5 m) thick. One difference was that in all but a few examples of this type of bunker there were no frontal embrasures, the only such units being located on the sides to cope with flanking attacks. Embrasures were built in the front only in special cases and were then protected with heavy metal doors. The programme included the towns of Aachen and Saarbrücken, which were initially to the west of the line planned for the Limes Programm.

The line of the Luftverteidigungszone 'West' Programm continued parallel with the two other lines toward the east, and consisted mainly of concrete towers for Flak (anti-aircraft) guns, whose primary purpose was not so much to shoot down enemy aircraft but rather to force them to fly at a higher altitude, from which the accuracy of their bombing was significantly reduced. The Flak towers were protected from ground attack by the bunkers from the Limes Programm and Aachen-Saar Programm.

The Geldern Stellung lengthened the Siegfried-Linie to the north as far as Kleve on the Rhine river, and was designed and built after the start of World War II to extend Germany’s defence farther to the north from the line’s original terminus near Brüggen. The Geldern Stellung was simpler than the rest of the 'Siegfried-Linie', and for the most part comprised trench lines and weapons pits which were, however, extremely strongly built of concrete. For camouflage they were often built near farms.

Tank traps were also built for miles along the 'Siegfried-Linie' and were known as 'dragon’s teeth' or 'pimples' in reflection of their shape. These blocks of reinforced concrete extended in several rows on a single foundation, and there were typically two sorts of barrier: Type 1938 with four teeth getting higher toward the back, and Type 1939 with five such teeth. However, many other irregular lines of teeth were also built and, if the terrain made it possible, water-filled ditches were dug instead of tank traps.

The bunkers of the Grenzwach Programm were constructed mostly by private companies, but these could not provide the number of workers needed for the programmes that followed. The construction gap was therefore filled by the Organisation 'Todt', so-named for its founder, Fritz Todt. With this organisation’s help, huge numbers of workers (up to half a million at a time) were found to work on the 'Siegfried-Linie' despite the fact that working conditions were both arduous and dangerous, and the monotony of the work persuaded many of the pre-war workers to leave the Organisation 'Todt'.

The German armaments industry was never able to deliver the quantity of armour which was required for the mounting of weapons in the bunkers, which greatly reduced the bunkers' military value. The armour-plated sections included the embrasures and their shutters, as well as armoured cupolas for 360° defence. Germany depended on other countries to provide the metals (most importantly nickel and molybdenum) other than iron for the manufacture of armour, so the armour was either omitted or replaced by lower-quality materials. The bunkers were nonetheless completed with pieces of artillery, but these were older weapons which other wartime experience revealed to be inadequate, and were therefore often removed. The larger-calibre and more modern weapons required for an effective defence capability were too massive for retrofitting in the bunkers.

Despite the fact that it was France which declared war on Germany in September 1939, there was no major combat along the 'Siegfried-Linie' at the start of the 'Phoney War' of 1939/40. After the end of Germany’s 'Sichelschnitt' and 'Rot' (iii) offensives to the west in May and June 1940, all the transportable weapons were removed from the 'Siegfried-Linie' for other service, and the concrete bunkers and tank traps were effectively abandoned, the bunkers often being adapted for storage.

With the start of 'Overlord' in June 1944, Germany faced war in the west once again, and on 24 August Hitler ordered renewed construction of the 'Siegfried-Linie'. Some 20,000 slave labourers and members of the Reichsarbeitsdienst (national labour service, mostly 14/16-year old boys) tried to recreate the line as an effective defence for Germany’s western frontier. Local persons were also conscripted for the work, mostly in the construction of anti-tank ditches. The work was greatly hampered, and indeed rendered virtually impossible, by the attentions of the Allies' overwhelming tactical air power. During construction it was already clear that the bunkers could no longer hope to withstand the altogether more capable armour-piercing weapons which had been developed in the war.

As the 'Siegfried-Linie' was being reactivated, small concrete 'Tobruk bunkers' (one/two-man dugouts) were added along the edge of the defended area.

It was in August 1944 that the first clashes took place along the 'Siegfried-Linie'. The section of the line which saw the most widespread fighting that of the Hürtgenwald, in the Eifel region some 12.5 miles (20 km) to the south-east of Aachen. The battle in this confusing, heavily forested area claimed large numbers of lives on each side. After the Battle of the Hürtgenwald, the focus of combat on the Western Front switched to the 'Battle of the Bulge', starting at the area to the south of the Hürtgenwald between Monschau and the Luxembourgois town of Echternach. There were major clashes in other parts of the 'Siegfried-Linie'. Soldiers in many of the bunkers refused to surrender, fearing German courts martial for cowardice more than Allied attack, and in such attempts at sustained defence most German soldiers paid with their lives as the bunkers were no effective defence. It was during the spring of 1945 that the last 'Siegfried-Linie' bunkers fell to the Allied advance in the Saar and Hunsrück.

One of the most significant battles in and around the 'Siegfried-Linie' was that Aachen, which was fought by US and German forces between 2 and 21 October 1944. The city had been incorporated into the 'Siegfried-Linie', and the Allies hoped to capture it quickly and advance into the industrialised region of the 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. This was one of the largest urban battles fought by US forces in World War II, and Aachen became the first city on German soil to be captured by the Allies. The battle ended with a German surrender, but their tenacious defence significantly disrupted Allied plans for the advance into Germany.

In overall terms, by September 1944 the Western Allies had reached Germany’s western border which, as noted above, was protected by the 'Siegfried-Linie'. On 17 September, British, US and Polish forces launched the 'Market' and 'Garden' operations in an ambitious undertaking to outflank the 'Siegfried-Linie' by crossing the lower part of the Rhine river in the German-occupied Netherlands. The failure of this undertaking combined with a major supply problem resulting from the long distances achieved in the rapid drive through France, brought an end to the headlong Allied race toward Berlin. German casualties in France had been high: Generalfeldmarschall Walter Model estimated that his notional 74 divisions had the actual strength of just 25 divisions, but the Western Allies' logistical problems now afforded the Germans a respite, which they used to begin rebuilding their strength. In September, the German high command’s reinforcement of the 'Siegfried-Linie' raised the troop strength to an estimated 230,000 soldiers, including 100,000 fresh troops; and whereas at the start of the month the Germans had only 100 armoured fighting vehicles in the west, by its end they had about 500. As men and equipment continued to flow into the 'Siegfried-Linie', the Germans were able to establish an average defensive depth of 3.1 miles (5 km).

The Supreme Headquarters Allied Expeditionary Force (SHAEF), under the command of General Dwight D. Eisenhower, aimed to seize the Ruhr, Germany’s industrial heartland, and within this overall concept Lieutenant General George S. Patton’s US 3^rd Army was tasked to occupy the French region of Lorraine, while Lieutenant General Courtney Hodges’s US 1^st Army was ordered to break through the front near Aachen. Believing that this city was held by only a small garrison, Hodges had initially hoped to bypass the city, leaving it to surrender once isolated.

In itself, Aachen possessed little military value as it was not a major centre of war production. Its population of around 165,000 had not been subject to heavy bombing by the Allies. However, the city was an important symbol to both the Nazi regime and the German people: it was the first German city threatened by an enemy during World War II, and was also the historic capital of Charlemagne, founder of the 'First Reich'. As such, Aachen was of great psychological value.

Aachen and its sector of the front were shielded by the 'Siegfried-Linie'. In several areas, the German defences were more than 10 miles (16 km) deep. Learning from their bitter experience on the Eastern Front, the Germans had positioned their main line of resistance down the centre of towns located in the overall defensive wall, taking advantage of narrow streets to limit the mobility of enemy armoured vehicles. Despite the low quality of many of the troops manning them, the fortifications protecting Aachen and the Ruhr were a formidable obstacle to any advance by the US forces, who saw a breakthrough in this sector as crucial as the terrain behind Aachen was generally flat, and therefore highly favourable to continued operations by the Allies' motorised formations.

Fighting in the area round Aachen began as early as the second week of September, in a period known to the Germans as the 1^st Battle of Aachen'. At this time, the city was defended by Generalleutnant Gerhard von Schwerin’s 116^th Panzerdivision, and the proximity of Allied forces had persuaded most of the city’s officials had departed even before the civilian evacuation was over. Instead of continuing the evacuation, von Schwerin had decided that the best option was to surrender the city to the Allies, but before he could deliver a letter of capitulation he had written, on 13 September von Schwerin was ordered to launch a counterattack against the US forces penetrating in the area to the south-west of Aachen. von Schwerin complied, using elements of his Panzergrenadier forces. von Schwerin’s letter fell into the hands of Hitler, who ordered the general’s immediate arrest. von Schwerin was replaced by Oberst Heinrich Voigtsberger. Major General J. Lawton Collins’s US VII Corps continued to probe the German defences, despite the resistance encountered on 12/13 September, and between 14 and 16 September Major General Clarence R. Huebner’s US 1^st Division continued its advance in the face of strong defences and repeated counterattacks, ultimately creating a half-moon arc around the city. This slow advance came to a halt late in September, largely as a result of logistical difficulties and the diversion of existing fuel and ammunition supplies for 'Market' and 'Garden'.

The Germans took advantage of the respite thus afforded to withdraw from the line SS-Brigadeführer und Generalmajor der Waffen-SS Wilhelm Mohnke’s 1^st SS Panzerdivision 'Leibstandarte Adolf Hitler', SS-Brigadeführer und Generalmajor der Waffen-SS Heinz Lammerding’s 2^nd SS Panzerdivision 'Das Reich', SS-Sturmbannführer Hubert Meyer’s 12^th SS Panzerdivision 'Hitlerjugend' and Generalleutnant Harald Freiherr von Elverfeldt’s 9^th Panzerdivision. In October, responsibility for the defence of the Aachen sector was given to General Friedrich Köchling’s LXXXI Corps. This included Generalmajor Wolfgang Lange’s 183^rd Volksgrenadierdivision, Oberst Gerhard Wilck’s 246^th Volksgrenadierdivision, Generalmajor Gerhard Engel’s 12^th Division, Generalleutnant Vollrath Lübbe’s 49^th Division. Together with Oberstleutnant F. H. Musculus’s attached 108^th Panzerbrigade and Major Gernard Willing’s 506^th schwere Panzerabteilung, these numbered about 20,000 men and 11 tanks. Köchling was also promised a re-formed 116^th Panzerdivision and Generalleutnant Walter Denkert’s 3^rd Panzergrenadierdivision , numbering 24,000 men. The 246^th Volksgrenadierdivision replaced the 116^th Panzerdivision within Aachen, the 183^rd Volksgrenadierdivision and 49^th Division defended the northern approaches to the city, and the 12^th Division was positioned to the south of the city. On 7 October, elements of the 1^st SS Panzerdivision 'Leibstandarte Adolf Hitler' were released to strengthen Aachen’s defences.

German reinforcements continued to arrive, but even so the formations and units of the LXXXI Corps suffered heavily: the 12^th Division lost half its combat strength between 16 and 23 September, and the 49^th Division and 275^th Division had to be withdrawn to recuperate. While German infantry divisions generally had generally possessed a strength of between 15,000 and 17,000 men at the start of World War II, this had gradually been reduced to an official size of 12,500 men, and by November 1944 the average actual strength of a division was 8,761 men. In an attempt to cope with the army’s manpower shortages, Volksgrenadier divisions were created in 1944. The average strength of these new formations was a little more than 10,000 men. Within each Volksgrenadier division, about one quarter of the men were experienced veterans, half were fresh conscripts and convalescents, and the final quarter were transferees from the air force and navy. These divisions often received the newest small arms, but lacked adequate artillery and motorised vehicles, which severely curtailed their tactical utility. In the case of the LXXXI Corps, the 183^rd Volksgrenadierdivision had 643 men over establishment but had been activated only in September and therefore had been able to undertake only the most limited training. The 246^th Volksgrenadierdivision was in a similarly parlous operational condition, many of its personnel having received fewer than 10 days of infantry training. All of these deficiencies of personnel were offset somewhat by the inherent strength of the well-planned, well-constructed fortifications surrounding Aachen.

The seizure of Aachen was allocated to Major General Leland S. Hobbs’s 30^th Division, with the 743^rd Tank Battalion attached, of Major General Charles H. Corlett’s XIX Corps and Huebner’s 1^st Division of Collins’s VII Corps. The 30^th Division was to be aided by Major General Ernest N. Harmon’s 2^nd Armored Division, which would exploit the 30^th Division’s penetration of the 'Siegfried-Linie', while their flanks were protected by Major General Leonard T. Gerow’s 29^th Division. In the south, the 1^st Division was supported by Major General Louis A. Craig’s 9^th Division and Major General Maurice Rose’s 3^rd Armored Division. All of these formations had utilised the brief respite in the fighting during the last two weeks of September to rest and refit, in the process absorbing a large number of replacements. By 1 October, more than 70% of the men of the 1^st Division were replacements, and the last two weeks of September were used to improve these men’s urban fighting and weapons skills.

The forthcoming offensive’s plan called for both infantry divisions to avoid street fighting in Aachen, however, but instead to effect a junction to the east of Aachen and thereby encircle it, then allocating a relatively small force to capture the city even as the bulk of US forces continued their drive to the east.

Although US units were usually able to replenish their numbers quickly, the replacements rarely had sufficient tactical training, and many of the junior officers lacked adequate tactical and leadership abilities. Some tank drivers reached the European theatre without having so much as driven a car before, and some tank commanders had to teach their men how to load and fire their guns in the field before they could enter combat. The US replacement system, which focused more on quantity than quality, meant that most freshly arrived troops were not properly trained for combat, so it was not unusual for half of any unit’s replacements to become casualties within the first few days of combat. These tremendous front-line losses required still more men to be fed into the fighting: for instance, a freshly reinforced battalion of the 28^th Division was immediately thrown into direct assaults against Aachen to buttress the depleted 1^st Division during the final stages of the battle between 18 and 21 October.

These ground forces were supported from the air by the warplanes of Major General Hoyt S. Vandenberg’s US 9^th Army Air Force, which had pinpointed three quarters of the pillboxes along the front and planned an opening bombardment including 360 bombers and 72 fighters; other aircraft would be used for a second wave of aerial bombardment, which included the use of napalm. As the Germans could field only a comparatively small number of anti-aircraft batteries and the army could count only only a severely limited level of air support by the Luftwaffe, Allied domination of the sky over Aachen was almost complete.

For six days before the start of the US offensive, Allied heavy artillery targeted the German defences in the area round Aachen. The heavy bombardment forced the LXXXI Corps to halt all daylight personnel and supply movements, but had little effect on the pillboxes and strongpoints. The opening aerial bombardment on 2 October also caused little damage to German defensive positions: the 450 aircraft committed in the first wave failed to register a single direct hit on any German pillbox, along the problems being the fact that their targets had been largely obscured by thick smoke from the Allied artillery barrage. As the aircraft finished their initial assault, the artillery resumed shelling the German front line, firing 18,696 rounds from 372 guns in some 120 minutes.

In the north, the 30^th Division began its advance on 2 October, using the division’s heavy artillery to target German pillboxes. Even so, it took an average of 30 minutes to capture a single pillbox. The Americans found that if they failed to press on without delay to the next pillbox, the Germans counterattacked. The division had not expected strong resistance, and one company lost 87 men in 60 minutes while another lost 93 out of 120 men to German artillery fire. Even so, the attackers were slowly able to cross the Wurm river and use flamethrowers and explosive charges to tackle German pillboxes. By the afternoon of 2 October, elements of the 30^th Division had breached some of the German defences to reach Palenberg. Here the US infantrymen had to advance in house-to-house combat, in the process fighting a number of bloody fights using hand grenades. The fighting in the town of Rimburg was equally ferocious: US armour had been unable to across the Wurm river, and so could not provide fire support to infantrymen who were attempting to storm a mediaeval castle being used as a fort by the Germans. The 30^th Division subdued about 50 pillboxes on the first day of its advance, often having to encircle the structure before attacking from the rear. The division’s effort was aided by the 29^th Division’s diversionary attacks on the northern flank, leading the Germans to believe that that was the primary US attack. On the night of 2/3 October, the 902^nd Sturmgeschützabteilung was ordered to launch a counterattack against the 30^th Division, but the weight of US artillery fire delayed the start of the raid, which ultimately failed.

Although US armour became available to support the advance on 3 October, the attacking forces were brought to an abrupt halt by several German counterattacks. Rimburg was taken on the second day of the offensive, but penetration of the German defences remained slow as M4 Sherman tanks and M12 155-mm (6.1-in) self-propelled guns arrived to blast pillboxes at pointblank range. Fighting had also begun for the town of Übach, where US tanks rushed in to take the town before being pinned by German artillery fire. Fierce counterattacks followed, with US artillery fire narrowly preventing the Germans from retaking the town. By the end of the day, the crossing of the Wurm river and the establishment of a bridgehead had cost the 30^th Division some 300 men killed and wounded.

German forces continued their counterattacks on Übach, suffering heavy casualties to US artillery and infantry fire. Although their failure to retake Übach had by now persuaded German commanders that they lacked the strength to conduct an effective defence of the approaches to Aachen, the counterattacks did pin US units which could otherwise have pressed the advance. On 4 October, the Allied advance was limited, with only the towns of Hoverdor and Beggendorf taken. The Americans had lost about 1,800 men in the three days of combat up to this time. Better progress was made on 5 October, as the 30^th Division’s 119^th Regiment took Merkstein-Herbach. On next day the Germans launched another counterattack against Übach, but were again unable to dislodge the Americans. The German armour could not cope with the overwhelming numerical superiority of the US tanks and, as a last-ditch effort to halt the advance, the Germans began concentrated attacks on US positions with whatever artillery and aircraft they could concentrate. The Germans found themselves strongly hindered by a shortage of reserves, although Köchling was able to deploy a detachment of PzKpfw VI Tiger heavy tanks to the town of Alsdorf in an attempt to seal off the US penetration of Aachen’s northern defences.

A German counterattack began on 8 October with a force based on one infantry regiment, one assault battalion, a Kampfgruppe of the 108^th Panzerbrigade and about 40 armoured fighting vehicles gathered from several units. Although struck by US artillery fire, the German assault’s left wing cut off a US platoon, while the right wing reached a road junction to the north of Alsdorf. A platoon of Sherman medium tanks supporting an attack on Mariadorf suddenly found itself attacked from the rear, and wase able to repel the Germans only after heavy fighting. Two StuG IV self-propelled assault guns and a squad of infantry entered Alsdorf, where they were heavily counterattacked. Although the two assault guns evaded the US tanks, they were finally engaged by US infantry and forced back to their starting point. With casualties mounting and the Americans drawing closer, the German high command transferred Denkert’s 3^rd Panzergrenadierdivision to Aachen, followed by SS-Obergruppenführer und General der Waffen-SS Georg Keppler’s I SS Panzerkorps, which included the 116^th Panzerdivision and the 101^st SS schwere Panzerabteilung that was part of the 1^st SS Panzerdivision 'Leibstandarte Adolf Hitler'.

In the south, the 1^st Division moved over to its offensive on 8 October, aiming to capture Verlautenheide and Hill 231 ('Crucifix Hill') near Ravelsberg. The US attack was preceded by a massive artillery bombardment, which greatly aided the swift American seizure of the planned objectives. By 10 October the 1^st Division had reached the position designated for its junction with the 30^th Division. This success was met with the inevitable German counterattack toward Hill 231, which became the location of an intense firefight that ended with the Germans leaving more than 40 dead and 35 prisoners. Despite the fact that repeated German counterattacks slowed its progress, the 1^st Division took the high ground surrounding Aachen.

On 10 October Huebner sent an ultimatum to the German forces in Aachen, threatening to bomb the city into submission if the garrison did not surrender, but the German commander refused to do so. US artillery then began to deluge the city on the following day, firing an estimated 5,000 rounds. The city was also subjected to intense bombing by US aircraft.

US casualties were increasing as a result of both frequent German counterattacks and the human cost of storming pillboxes. The Germans had spent the night of 10/11 October turning cellars of houses in the town of Bardenberg into fortified pillboxes, and the following US attacks were checked. Huebner pulled back the attacking units and decided instead to shell the city into submission. On 12 October, the Germans launched a major counterattack against the 30^th Division, but this was disrupted by heavy artillery fire and well-sited anti-tank defences. At the village of Birk, a three-hour fight broke out between German tanks and a single US Sherman tank. The Sherman managed to knock out a PzKpfw IV tank and compel another to pull back, but the US tank was soon attacked by other German armoured vehicles. This lone tank was eventually joined by elements of the 2^nd Armored Division, and the Germans were driven from the town. The 30^th Division soon found itself in defensive positions all along its front, however, but was ordered to continue its drive to the south for its intended junction with the 1^st Division. In pursuit of this objective, two infantry battalions of the 29^th Division were attached to the 30^th Division.

Farther to the south, on the same day two German infantry regiments attempted to retake 'Crucifix Hill' from the Americans of the 1^st Division: in the course of fierce fighting, the Germans gained temporary control of the hill, but had been dislodged by the end of the day, with both regiments virtually destroyed. Between 11 and 13 October, Allied aircraft bombed Aachen, selecting targets closest to the US lines. On 14 October, the 26^th Infantry was ordered to clear an industrial zone on the edge of Aachen in preparation for the attack on the city itself. On 15 October, in an effort to widen the gap between the two havles of the US pincer movement, the Germans again counterattacked the 1^st Division: although a number of heavy tanks succeeded in breaking through US lines, the bulk of the German forces was destroyed by artillery fire and air support. On the next day the Germans attempted to mount local counterattacks with the 3^rd Panzergrenadierdivision but suffered heavy losses and were forced to call off further offensive action.

The 30^th Division, with elements of the 29^th Division and 2^nd Armored Division, continued its push to the south between 13 and 16 October, in the sector of Würselen villager, but even with the aid of heavy air support was not able to break through the German defences and effect a junction with Allied forces to the south. The Germans took advantage of the narrow nature of the front to pound advancing attackers with artillery, and progress remained slow as German tanks used houses as bunkers to surprise and overwhelm US infantrymen. Hobbs, the commander of the 30^th Division, then attempted to outflank the German defences by attacking in another sector with two infantry battalions, and the success of this attack allowed the 30^th and 1^st Divisions to link on 16 October. The fighting had so far cost the XIX Corps more than 400 dead and 2,000 wounded, some 72% of the casualties in the 30^th Division. The Germans had also suffered very heavily, by 14 October losing some 630 men killed and about 4,400 wounded; another 600 men were lost in the 3^rd Panzergrenadierdivision's counterattack on the 1^st Division on 16 October.

Requiring the bulk of its strength to stave off German counterattacks and secure the area around Aachen, the 1^st Division was able to allocate only one regiment to take the city of Aachen. The task fell to Colonel John F. R. Seitz’s 26^th Infantry, which had available for the task only two of its three battalions. Using machine guns and flamethrowers, the 2/26^th and 3/26^th Infantry were initially supported by a few tanks and a single 155-mm (6.1-in) howitzer. The city was defended by about 5,000 Germans, who including converted navy, air force and city police personnel. Most of the German troops were inexperienced and untrained, and were supported by a mere handful of tanks and assault guns. A German advantage, however, was the fact that Aachen’s defenders exploit the maze of streets comprising the centre of the historic city.

The 26^th Infantry’s initial attack on 13 October provided important information into the nature of the fighting which was now required. US infantrymen had been ambushed by German defenders using sewers and cellars, forcing the advancing American troops to clear each opening before continuing down any street, while Sherman tanks found it impossible to manoeuvre to suppress German fire. German civilians were cleared as the 26^th Infantry advanced, and no Germans were permitted to remain in the Americans' rear. Success in Aachen was measured by the number of houses captured, as the advance proved to be sluggish. In order to cope with the thick walls of the city’s older buildings, the 26^th Infantry made use of its howitzer at pointblank range to destroy German fortifications: howitzer fire blasted passageways that allowed the infantry to advance from building to building without having to enter the city’s streets, where they could be pinned down by German fire. Sherman tanks were ambushed, wherever they entered intersections, by concealed German anti-tank guns. Soon after this, US tanks and other armoured vehicles began to advance with greater caution, often firing at buildings ahead of the accompanying infantry to clear them of possible defenders. Pinned on the surface by Allied aircraft, German infantry made extensive use of sewers to deploy behind US units and attack them from the rear. German resistance was fierce as they launched small counterattacks and used armour to halt US movement.

On 18 October, the 3/26^th Infantry readied itself to attack the Hotel Quellenhof, which was one of the last areas of resistance in the city. US tanks and other guns were firing on the hotel, which was the city’s defence headquarters, at pointblank range. That night, 300 men of a Waffen-SS battalion were able to reinforce the hotel and drive back several attacks on the building. A determined German counterattack also managed to overrun several US infantry positions outside the hotel, and this effected a temporary easing of pressure on the Hotel Quellenhof before being driven back by US mortar fire.

Two events then aided the final US advance: firstly, in order to lessen front-line infantry casualties, it was decided to shell the remaining German strongpoints with 155-mm (6.1-in) artillery; and secondly, to assist the 1^st Division, one battalion of the 28^th Division’s 110^th Infantry was shifted from the V Corps' sector on 18 October to close a gap between 26^th Infantry forward elements within the city. The defensive mission of this new battalion was then revised on 19/20 October to close support of the urban assault as what was in effect the depleted regiment’s missing third battalion. On 21 October, men of the 26^th Infantry, supported by the reinforced battalion of the 110^th Infantry, finally took the centre of Aachen. On the same day, the surrender in the Hotel Quellenhof of the last German cohesive force brought to an end the battle for the city of Aachen.

The Battle of Aachen had cost both the Americans and the Germans dearly: the former had suffered more than 7,000 casualties, while the latter had lost more than 5,000 casualties and 5,600 men taken prisoner. Since 2 October, the 30^th Division had lost about 3,000 men killed and wounded, while the 1^st Division had suffered at least 1,350 casualties in the form of 150 men killed and 1,200 wounded. The Germans had lost another 5,100 casualties during the fighting in Aachen itself, including 3,473 men taken prisoner. During the battle, the Germans had lost two complete divisions and had suffered the severe depletion of another eight, that latter including three fresh infantry divisions and a single refitted armoured division. This was attributable largely to the manner in which the Germans had fought, as although an equivalent of 20 infantry battalions had been used during various counterattacks against the 30^th Division alone, on average each separate attack involved only two infantry regiments. The conflict was notable, the Germans had learned, for the fact that the US forces had revealed a capability for the use of indiscriminate but overwhelming artillery fire support and armour.

Even so, the German resistance in Aachen upset Allied plans to continue their eastward advance. Following the end of fighting in Aachen, the US 1^st 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 opening the way to Berlin. This resulted in the Battle of the Hürtgen Forest, which was to prove still more difficult than the Battle of Aachen.