Operation Cobra

Following the Allied invasion of Normandy on June 6th 1944, progress inland was to become very slow. To facilitate the Allied build-up in France and to secure room for further expansion, the deep water port of Cherbourg on the western flank of the American sector and the historic town of Caen in the British and Canadian sector to the east, were early objectives. The original plan for the Normandy campaign envisioned strong offensive efforts in both sectors, in which the Second Army would secure Caen and the area south of it and the First US Army would “wheel round” to the Loire.

General Sir Bernard Montgomery—commanding all Allied ground forces in Normandy—intended Caen to be taken on D-Day, while Cherbourg was expected to fall 15 days later. The Second Army was to seize Caen and then form a front to the southeast, extending to Caumont, to acquire airfields and protect the left flank of the First US Army as it moved on Cherbourg. Possession of Caen and its surroundings would also give the Second Army a suitable staging area for a push south to capture Falaise, which could be used as the pivot for a swing east to advance on Argentan and then the Touques River. The capture of Caen has been described by the British official historian Lionel Ellis as the most important D-Day objective assigned to the British I Corps. Ellis and Chester Wilmot called the Allied plan “ambitious” since the Caen sector contained the strongest defences in Normandy.

The initial attempt by I Corps to reach the city on D-Day was blocked by elements of the 21st Panzer Division and with the Germans committing most of the reinforcements sent to meet the invasion to the defence of Caen, the Anglo-Canadian front rapidly congealed short of the Second Army’s objectives. Operation Perch in the week following D-Day and Operation Epsom brought some territorial gains and depleted its defenders but Caen remained in German hands until Operation Charnwood, when the Second Army managed to take the northern part of the city up to the River Orne in a frontal assault.

The successive Anglo-Canadian offensives around Caen kept the best of the German forces in Normandy, to the eastern end of the Allied lodgement but even so the First US Army made slow progress against dogged German resistance. In part, operations were slow due to the constraints of the bocage landscape of densely packed banked hedgerows, sunken lanes and small woods, for which U.S. units had not trained. With no ports in Allied hands, all reinforcement and supply had to take place over the beaches via the two Mulberry harbours and was at the mercy of the weather. On 19 June, a severe storm descended on the English Channel, lasting for three days and causing significant delays to the Allied build-up and the cancellation of some operations. The First US Army advance in the western sector was eventually halted by Bradley before the town of Saint-Lô, to concentrate on the seizure of Cherbourg. The defence of Cherbourg consisted largely of four German battlegroups formed from the remnants of units that had retreated up the Cotentin peninsula but the port defences had been designed principally to meet an attack from the sea. Organized German resistance ended only on 27 June, when the 9th US Infantry Division managed to reduce the defences of Cap-de-la-Hague, north-west of the port. Within four days, VII Corps resumed the offensive toward Saint-Lô, alongside XIX Corps and VIII Corps, causing the Germans to move more armour into the U.S. sector.

The originator of the idea for Operation Cobra is disputed. According to Montgomery’s official biographer, the foundation of Operation Cobra was laid on 13 June. Planning was immensely aided by detailed Ultra intelligence which supplied up-to-date decodes of communications between Oberkommando der Wehrmacht (OKW, the German armed forces high command) and Hitler’s generals. Montgomery’s plan at that time called for the U.S. First Army to take Saint-Lô and Coutances and then make two southward thrusts; one from Caumont toward Vire and Mortain and the other from Saint-Lô toward Villedieu and Avranches. Although pressure was to be kept up along the Cotentin Peninsula towards La Haye-du-Puits and Valognes, the capture of Cherbourg was not the priority. With the capture of Cherbourg by VII Corps on 27 June, Montgomery’s initial timetable was overtaken by events and the thrust from Caumont was never adopted.

Following the conclusion of Operation Charnwood and the cancellation of the First Army offensive towards Saint-Lô, Montgomery met with Bradley and Dempsey on 10 July to discuss plans for the 21st Army Group. Bradley said that progress on the western flank was very slow but that plans had been laid for another breakout attempt, codenamed Operation Cobra, to be launched by the First Army on 18 July. Montgomery approved the plan and that the strategy would remain the diversion of German attention from the First Army to the British and Canadian sector. To accomplish this, Operation Goodwood was planned and Eisenhower ensured that both operations would have the support of the Allied strategic bombers.

On 12 July, Bradley briefed his commanders on the Cobra plan, which consisted of three phases. The main effort would be under the control of VII Corps. In the first phase, the breakthrough attack would be conducted by the 9th Infantry Division and the 30th Infantry Division, which would break into the German defensive zone and then hold the flanks of the penetration while the 1st Infantry Division and 2nd Armoured Division pushed into the depth of the position until resistance collapsed. The 1st Infantry Division “was to take Marigny, with this objective exploited by a stream of General Watson’s 3rd Armoured Division armour that would move south toward Coutances”. The 2nd Armoured Division—part of “Collins’ exploitation force” of the 2nd Armoured Division in the east of the VII Corps sector and the “1st Infantry Division reinforced by Combat Command B of the 3rd Armoured division in the west”—would “pass through the 30th Infantry Division sector … and guard the overall American left flank.” If VII Corps succeeded, the western German position would become untenable, permitting a relatively easy advance to the southwest end of the bocage to cut off and seize the Brittany peninsula. First Army intelligence estimated that no German counterattack would occur in the first few days after Cobra’s launch and that if they did later, they would be no more than battalion-sized operations.

Cobra was to be a concentrated attack on a 6,400m front, unlike previous American broad front offensives and would have a mass of air support. Fighter-bombers would concentrate on hitting forward German defences in a 230m belt immediately south of the Saint-Lô–Periers road, while General Spaatz’s heavy bombers would bomb to a depth of 2,300 m behind the German main line of resistance.[55] It was anticipated that the physical destruction and shock value of a short, intense preliminary bombardment would greatly weaken the German defence so in addition to divisional artillery, Army- and Corps-level units would provide support, including nine heavy, five medium and seven light artillery battalions. Over 1,000 divisional and corps artillery pieces were committed to the offensive and approximately 140,000 artillery rounds were allocated to the operation in VII Corps, with another 27,000 for VIII Corps.

To overcome the constraints of the bocage that had made attacks so difficult and costly for both sides, Rhino modifications were made to some M4 Sherman, M5A1 Stuart tanks and M10 tank destroyers, by fitting them with hedge-breaching ‘tusks’ that could force a path through hedgerows. German tanks remained restricted to the roads but U.S. armoured vehicles could manoeuvre more freely, although the effectiveness of the devices was exaggerated. By the eve of Cobra, 60 percent of the tanks of the First Army had the rhino modification. To preserve operational security, Bradley forbade their use until Cobra was launched. In all, 1,269 M4 medium tanks, 694 M5A1 light tanks and 288 M10 tank destroyers were available.

On 18 July, the British VIII and I Corps—to the east of Caen—launched Operation Goodwood. The offensive began with the largest air bombardment in support of ground forces yet, with more than 1,000 aircraft dropping 6,000 short tons of high explosive and fragmentation bombs from low altitude. German positions to the east of Caen were shelled by 400 artillery pieces and many villages were reduced to rubble but German artillery further to the south, on the Bourguébus Ridge, was outside the range of the British artillery and the defenders of Cagny and Émiéville were largely unscathed by the bombardment. This contributed to the losses suffered by Second Army, which sustained over 4,800 casualties. Principally an armoured offensive, between 250 and 400 British tanks were put out of action, although recent examination suggests that only 140 were completely destroyed with an additional 174 damaged. The operation remains the largest tank battle ever fought by the British Army and resulted in the expansion of the Orne bridgehead and the capture of Caen on the south bank of the Orne.

Simultaneously, the II Canadian Corps on the western flank of Goodwood began Operation Atlantic to strengthen the Allied foothold along the banks of the Orne and take Verrières Ridge to the south of Caen. Atlantic made initial gains but ran out of steam as casualties mounted. Having cost the Canadians 1,349 men and with the heavily defended ridge firmly in German hands, Atlantic was closed down on 20 July. At Montgomery’s urging, “strongly underlined in the Supreme Commander’s communications to Montgomery”, the II Canadian Corps commander, Lieutenant-General Guy Simonds, began a second offensive a few days later, codenamed Operation Spring. This had the limited but important aim of tying down German units to prevent them from being transferred to the American sector, although Simonds took the opportunity to make another bid for Verrières Ridge. Again the fighting for Verrières Ridge proved extremely bloody for the Canadians, with 25 July marking the costliest day for a Canadian battalion—The Black Watch of Canada—since the Dieppe Raid of 1942. A counterstroke by two German divisions pushed the Canadians back past their start lines and Simonds had to commit reinforcements to stabilize the front. With Goodwood, the Canadian operations caused the Germans to commit most of their armour and reinforcements to the eastern sector. Operation Spring—despite its cost—had drawn the 9th SS Panzer Division away from the U.S. sector on the eve of Operation Cobra. Only two Panzer divisions with tanks now faced the First Army. Seven Panzer divisions with tanks were around Caen, far away from Operation Cobra as were all the heavy Tiger tank battalions and the three Nebelwerfer brigades in Normandy.

Bradley and Collins near Cherbourg

To gain good terrain for Operation Cobra, Bradley and Collins conceived a plan to push forward to the Saint-Lô–Periers road, along which VII and VIII Corps were securing jumping-off positions. On 18 July, at a cost of 5,000 casualties, the American 29th and 35th Infantry Divisions managed to gain the vital heights of Saint-Lô, driving back General der Fallschirmtruppen Eugen Meindl’s II Parachute Corps. Meindl’s paratroopers, together with the 352nd Infantry Division were now in ruins, and the stage for the main offensive was set. Due to poor weather conditions that had also been hampering Goodwood and Atlantic, Bradley decided to postpone Cobra for a few days—a decision that worried Montgomery, as the British and Canadian operations had been launched to support a breakout attempt that was failing to materialize. By 24 July the skies had cleared enough for the start order to be given, and 1,600 Allied aircraft took off for Normandy. However, the weather closed in again over the battlefield. Under poor visibility conditions, more than 25 Americans were killed and 130 wounded in the bombing before the air support operation was postponed until the following day. Some enraged soldiers opened fire on their own aircraft, a not uncommon practice in Normandy when suffering from friendly fire.

Operation Cobra 25–29 July 1944

After the one-day postponement, Cobra got underway at 09:38 on 25 July, when around 600 Allied fighter-bombers attacked strong points and enemy artillery along a 270 m -wide strip of ground located in the St. Lô area. For the next hour, 1,800 heavy bombers of the U.S. Eighth Air Force saturated a 6,000 yd × 2,200 yd area on the Saint-Lô–Periers road, succeeded by a third and final wave of medium bombers. Approximately 3,000 U.S. aircraft had carpet-bombed a narrow section of the front, with the Panzer-Lehr-Division taking the brunt of the attack. However, once again not all the casualties were German; Bradley had specifically requested that the bombers approach the target from the east, out of the sun and parallel to the Saint-Lô–Periers road, in order to minimize the risk of friendly losses, but most of the airmen instead came in from the north, perpendicular to the front line.[80] Bradley, however, had apparently misunderstood explanations from the heavy bomber commanders that a parallel approach was impossible because of the time and space constraints Bradley had set. Additionally, a parallel approach would not, in any event, have assured that all bombs would fall behind German lines because of deflection errors or obscured aim points due to dust and smoke. Despite efforts by U.S. units to identify their positions, inaccurate bombing by the Eighth Air Force killed 111 men and wounded 490. The dead included Bradley’s friend and fellow West Pointer Lieutenant General Lesley McNair—the highest-ranking U.S. soldier to be killed in action in the European Theatre of Operations.

By 11:00, the infantry began to move forward, advancing from crater to crater beyond what had been the German outpost line. Although no serious opposition was forecast, the remnants of Fritz Bayerlein′s Panzer Lehr—consisting of roughly 2,200 men and 45 armoured vehicles—had regrouped and were prepared to meet the advancing U.S. troops, and to the west of Panzer Lehr the German 5th Parachute Division had escaped the bombing almost intact. Collins’ VII Corps were quite disheartened to meet fierce enemy artillery fire, which they expected to have been suppressed by the bombing. Several U.S. units found themselves entangled in fights against strongpoints held by a handful of German tanks, supporting infantry and 88 mm guns—VII Corps gained only 2,000 m during the rest of the day. However, if the first day’s results had been disappointing, General Collins found cause for encouragement; although the Germans were fiercely holding their positions, these did not seem to form a continuous line and were susceptible to being outflanked or bypassed. Even with prior warning of the American offensive, the British and Canadian actions around Caen had convinced the Germans that the real threat lay there, and tied down their available forces to such an extent that a succession of meticulously prepared defensive positions in depth, as encountered during Goodwood and Atlantic, were not created to meet Cobra.

The St. Lô breakthrough, 25–31 July

On the morning of 26 July, the U.S. 2nd Armored Division and the 1st Infantry Division joined the attack as planned, reaching one of Cobra’s first objectives—a road junction north of Le Mesnil-Herman—the following day. Also on 26 July, VIII Corps entered the battle, led by the 8th U.S. Infantry Division and 90th U.S. Infantry Division. Despite clear paths of advance through the floods and swamps across their front, both divisions initially disappointed the First Army by failing to gain significant ground but first light the next morning revealed that the Germans had been compelled to retreat by their crumbling left flank, leaving only immense minefields to delay VIII Corps. By noon on 27 July, the 9th U.S. Infantry Division was also clear of any organized German resistance and was advancing rapidly.

Breakout and advance 28–30 July

By 28 July, the German defences across the U.S. front had largely collapsed under the full weight of the VII and VIII Corps advance and resistance was disorganized and patchy. The 4th Armoured Division (VIII Corps)—entering combat for the first time—captured Coutances but met stiff opposition east of the town and U.S. units penetrating into the depth of the German positions were counter-attacked by elements of the 2nd SS Panzer Division, 17th SS Panzergrenadier Division and the 353rd Infantry Division, seeking to escape entrapment. Around Roncey, P-47 Thunderbolts of the 405th Fighter Group destroyed a German column of 122 tanks, 259 other vehicles and 11 artillery pieces. An attack by British Typhoons close to La Baleine destroyed 9 tanks, 8 other armoured vehicles and 20 other vehicles. A counter-attack was mounted against the U.S. 2nd Armoured Division by German remnants but this was a disaster and the Germans abandoned their vehicles and fled on foot. Two columns of the 2nd SS Panzer Division were mauled by the U.S. 2nd Armoured Division. A column around La Chapelle was bombarded at point blank range by 2nd Armoured Division artillery. In two hours, American artillery fired over 700 rounds, into the column. The Germans suffered the loss of 50 dead, 60 wounded and 197 taken prisoner. Material losses were over 260 German combat vehicles destroyed. Beyond the town another 1,150 German soldiers were killed and the Germans lost 96 armoured combat vehicles and trucks. The U.S. 2nd Armoured Division destroyed 64 German tanks and 538 other German combat vehicles during Operation Cobra. The U.S. 2nd Armoured Division suffered 49 tank losses in the process. The 2nd Armoured Division also inflicted over 7,370 casualties on the Germans while suffering 914 casualties. At the beginning of Operation Cobra the German Panzer Lehr Division had only 2,200 combat troops, 12 Panzer IV and 16 Panthers fit for action and 30 tanks in various states of repair behind the lines. Panzer Lehr was in the path of Allied bombing that consisted of 1,500 bombers. The division suffered about 1,000 casualties during this bombardment. An exhausted and demoralized Bayerlein reported that his Panzer Lehr Division was “finally annihilated”, with its armour wiped out, its personnel either casualties or missing and all headquarters records lost.

Field Marshal Günther von Kluge Oberbefehlshaber West (commander of German forces on the Western Front)—was mustering reinforcements, and elements of the 2nd Panzer Division and the 116th Panzer Division were approaching the battlefield. The U.S. XIX Corps entered the battle on 28 July on the left of VII Corps and between 28 and 31 July became embroiled with these reinforcements in the fiercest fighting since Cobra began. During the night of 29/30 July near Saint-Denis-le-Gast, to the east of Coutances, elements of the 2nd Armoured Division found themselves fighting for their lives against a German column from the 2nd SS Panzer Division and 17th SS Panzergrenadier Division, which passed through the American lines in the darkness. Other elements of the 2nd Armoured Division were attacked near Cambry and fought for six hours; Bradley and his commanders knew that they were dominating the battlefield and such desperate assaults were no threat to the American position. When ordered to concentrate his division, Colonel Heinz Günther Guderian the senior staff officer of the 116th Panzer Division was frustrated by the high level of Allied fighter-bomber activity. Without receiving direct support from the 2nd Panzer Division as promised, Guderian stated that his panzergrenadiers could not succeed in a counterattack against the Americans. Advancing southward along the coast, later that day, the U.S. VIII Corps seized the town of Avranches—described by historian Andrew Williams as “the gateway to Brittany and southern Normandy”—and by 31 July XIX Corps had thrown back the last German counterattacks after fierce fighting, inflicting heavy losses in men and tanks. The American advance was now relentless, and the First Army was finally free of the bocage.

Operation Bluecoat, 30 July – 7 August

On 30 July, to protect Cobra’s flank and prevent the disengagement and relocation of further German forces, VIII Corps and XXX Corps of the Second Army began Operation Bluecoat southwards from Caumont toward Vire and Mont Pinçon. Bluecoat kept German armoured units fixed on the British eastern front and continued the wearing down of the strength of German armoured formations in the area. The breakthrough in the centre of the Allied front surprised the Germans, when they were distracted by the Allied attacks at both ends of the Normandy bridgehead. By the time of the American breakout at Avranches, there was little to no reserve strength left for Unternehmen Lüttich, which had been defeated by 12 August, leaving the 7th Army with no choice but to retire rapidly east of the Orne river, with a rear guard of the remaining armoured and motorized units, to allow time for the surviving infantry to reach the Seine. After the first stage of the withdrawal beyond the Orne, the manoeuvre collapsed for a lack of fuel, Allied air attacks and the constant pressure of the Allied armies, culminating in the encirclement of German forces in the Falaise pocket.


The U.S. advance following Cobra was extraordinarily rapid. Between 1 August and 4 August, seven divisions of Patton’s Third Army had swept through Avranches and over the bridge at Pontaubault into Brittany. The Westheer (German army in the west) had been reduced to such a poor state by the Allied offensives that, with no prospect of reinforcement in the wake of Operation Bagration, the Soviet summer offensive against Army Group Centre, very few Germans believed they could now avoid defeat. Rather than order his remaining forces to withdraw to the Seine, Adolf Hitler sent a directive to von Kluge demanding “an immediate counterattack between Mortain and Avranches” (Unternehmen Lüttich) to “annihilate” the enemy and make contact with the west coast of the Cotentin peninsula. Eight of the nine Panzer divisions in Normandy were to be used in the attack but only four (one of them incomplete) could be relieved from their defensive tasks and assembled in time. German commanders immediately protested that such an operation was impossible given their remaining resources but these objections were overruled and the counter-offensive, commenced on 7 August around Mortain. The 2nd, 1st SS and 2nd SS Panzer Divisions led the assault, although with only 75 Panzer IVs, 70 Panthers and 32 self-propelled guns. Hopelessly optimistic, the offensive was over within 24 hours, although fighting continued until 13 August.

By 8 August, the city of Le Mans—the former headquarters of the German 7th Army—had fallen to the Americans.

On 14 August, in conjunction with American movements northward to Chambois, Canadian forces launched Operation Tractable; the Allied intention was to trap and destroy the German 7th Army and 5th Panzer Army near the town of Falaise. Five days later, the two arms of the encirclement were almost complete; the advancing U.S. 90th Infantry Division had made contact with the Polish 1st Armoured Division and the first Allied units crossed the Seine at Mantes Gassicourt, while German units were fleeing eastward by any means they could find. By 22 August, the Falaise Pocket—which the Germans had been fighting desperately to keep open to allow their trapped forces to escape—was finally sealed, ending the Battle of Normandy with a major Allied victory. All German forces west of the Allied lines were now dead or in captivity and although perhaps 100,000 German troops escaped they left behind 40,000–50,000 prisoners and over 10,000 dead. A total of 344 tanks and self-propelled guns, 2,447 soft-skinned vehicles and 252 artillery pieces were found abandoned or destroyed in the northern sector of the pocket. The Allies were able to advance freely through the undefended territory and by 25 August all four Allied armies (First Canadian, Second British, First U.S., and Third U.S.) involved in the Normandy campaign were on the river Seine.

Ben Davidson

Hello, I have been studying all aspects of history for about 25 years. I have a BA History from the University of Bedfordshire. My historical areas of interest are anything really, but I specialise in 19th - 20th century Britain, America and Ireland. I am also strongly aligned with most military history, really enjoying WW2 and the US Civil War. Chuck in the king or queen and Bob's your uncle.

Leave a Reply

Your email address will not be published. Required fields are marked *