Operation Cobra - wikipedia Operation Cobra Operation Cobra Part of Operation Overlord ( the Battle of Normandy ) M4 Sherman tanks and infantrymen of the US 4th Armored Division in Coutances Date 25 -- 31 July 1944 Location Saint - Lô, Normandy, France 49 ° 06 ′ 55 '' N 1 ° 05 ′ 25 '' W ﻿ / ﻿ 49.115277 ° N 1.090277 ° W ﻿ / 49.115277 ; - 1.090277 ﻿ ( Saint Lo ) Coordinates : 49 ° 06 ′ 55 '' N 1 ° 05 ′ 25 '' W ﻿ / ﻿ 49.115277 ° N 1.090277 ° W ﻿ / 49.115277 ; - 1.090277 ﻿ ( Saint Lo ) Result Allied victory Belligerents United States Germany Commanders and leaders Bernard Montgomery Omar Bradley J. Lawton Collins Troy Middleton Charles H. Corlett Günther von Kluge Paul Hausser Eugen Meindl Strength 8 infantry divisions 3 armored divisions 2,451 tanks and tank destroyers 2 infantry divisions 1 parachute division 4 understrength Panzer divisions 1 Panzergrenadier division 190 tanks and assault guns Casualties and losses 1,800 casualties at least 109 medium tanks unknown number of light tanks and tank destroyers ~ 70 tanks and assault guns Operation Overlord Invasion of Normandy Prelude Atlantic Wall Bodyguard Fortitude Zeppelin Titanic Taxable, Glimmer & Big Drum Combined Bomber Offensive Pointblank Transport Plan Postage Able Tarbrush Tiger Fabius Initial airborne assault British sector Tonga Deadstick Merville Battery Mallard American sector Albany Boston Chicago Detroit Elmira Normandy landings American sector Omaha Utah Pointe du Hoc Anglo - Canadian sector Gambit Sword Juno Gold Port - en - Bessin Initial ground campaign American sector Brécourt Manor Graignes Hill 30 Saint - Lô Carentan Cherbourg Anglo - Canadian sector Caen Bréville Perch Villers - Bocage Le Mesnil - Patry Douvres Martlet Epsom Windsor Charnwood Jupiter 2nd Odon Atlantic Goodwood Verrières Ridge Breakout Cobra Spring Bluecoat Totalize Lüttich Tractable Hill 262 Chambois Falaise Brest Paris Air and sea operations Ushant La Caine Cherbourg Pierres Noires Audierne Bay Supporting operations Dingson Samwest Titanic Cooney Jedburgh Pluto Mulberry Dragoon Aftermath Cemeteries Operation Cobra was the codename for an offensive launched by the First United States Army ( Lieutenant General Omar Bradley ) seven weeks after the D - Day landings, during the Normandy Campaign of World War II. The intention was to take advantage of the distraction of the Germans by the British and Canadian attacks around Caen, in Operation Goodwood and break through the German defenses that were penning in his troops, while the Germans were unbalanced. Once a corridor had been created, the First Army would then be able to advance into Brittany, rolling up the German flanks once free of the constraints of the bocage country. After a slow start the offensive gathered momentum and German resistance collapsed as scattered remnants of broken units fought to escape to the Seine. Lacking the resources to cope with the situation, the German response was ineffectual and the entire Normandy front soon collapsed. Operation Cobra, together with concurrent offensives by the British Second Army and the Canadian First Army, was decisive in securing an Allied victory in the Normandy Campaign. Having been delayed several times by poor weather, Operation Cobra commenced on 25 July, with a concentrated aerial bombardment from thousands of Allied aircraft. Supporting offensives had drawn the bulk of German armored reserves toward the British and Canadian sector and coupled with the general lack of men and materiel available to the Germans, it was impossible for them to form successive lines of defense. Units of the U.S. VII Corps led the initial two - division assault, while other First Army corps mounted supporting attacks designed to pin German units in place. Progress was slow on the first day but opposition started to crumble once the defensive crust had been broken. By 27 July, most organized resistance had been overcome and the VII and VIII Corps advanced rapidly, isolating the Cotentin peninsula. By 31 July, XIX Corps had destroyed the last forces opposing the First Army, which emerged from the bocage. Reinforcements were moved west by Field Marshal Günther von Kluge and employed in various counterattacks, the largest of which, Unternehmen Lüttich ( Operation Liège ), was launched on 7 August between Mortain and Avranches. Although this led to the bloodiest phase of the battle, it was mounted by already exhausted and understrength units and was a costly failure. On 8 August, troops of the newly activated Third United States Army captured the city of Le Mans, formerly the German 7th Army headquarters. Operation Cobra transformed the high - intensity infantry combat of Normandy into rapid maneuver warfare and led to the creation of the Falaise pocket and the loss of the German position in northwestern France. Contents 1 Background 2 Planning 2.1 Supporting operations 2.2 Logistics 3 Allied offensive 3.1 Preliminary attacks 3.2 Main attack and breakthrough 25 -- 27 July 3.3 Breakout and advance 28 -- 31 July 3.4 Operation Bluecoat, 30 July -- 7 August 4 Aftermath 5 See also 6 Footnotes 7 Citations 8 References 9 External links Background Further information : Invasion of Normandy and Operation Overlord Following the successful Allied invasion of Normandy on 6 June 1944, progress inland was 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 ( Lieutenant - General Sir Miles Dempsey ) would secure Caen and the area south of it and the First US Army ( Lieutenant General Omar Bradley ) 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 - l'Éventé, to acquire airfields and protect the left flank of the First US Army as it moved on Cherbourg. Possession of Caen and its surroundings -- desirable for open terrain that would permit maneuver warfare -- 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 right to advance on Argentan and then the Touques River. Caen 's capture has been described by historian L.F. Ellis as the most important D - Day objective assigned to Lieutenant - General Crocker 's British I Corps. Ellis and Chester Wilmot called the Allied plan `` ambitious '' since the Caen sector contained the strongest defences in Normandy. Anglo - Canadian offensives in the Caen area after D - Day, from 6 June - 20 July 1944 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 defense of Caen, the Anglo - Canadian front rapidly congealed short of Second Army 's objectives. Operation Perch in the week following D - Day and Operation Epsom ( 26 -- 30 June ) brought some territorial gains and depleted its defenders but Caen remained in German hands until Operation Charnwood ( 7 -- 9 July ), 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, including most of the available armor, 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 port facilities in Allied hands, all reinforcement and supply had to take place over the beaches via the two Mulberry harbors 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 planned 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 defense of Cherbourg consisted largely of four battlegroups formed from the remnants of units that had retreated up the Cotentin peninsula but the port defenses 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 city. Within four days, VII Corps ( Major General J. Lawton `` Lightning Joe '' Collins ) resumed the offensive toward Saint - Lô, alongside XIX Corps and VIII Corps, causing the Germans to move additional armor into the U.S. sector. Planning Further information : Operation Cobra order of battle 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 ( Lieutenant - General Lawton Collins ) on 27 June, Montgomery 's initial timetable was soon outdated 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 admitted 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 be to draw German attention from the First Army to the British and Canadian sector. Dempsey was instructed to `` go on hitting, drawing the German strength, especially the armour, onto yourself -- so as to ease the way for Brad ( ley ) ''. To accomplish this, Operation Goodwood was planned and Eisenhower ensured that both operations would have the support of the Allied air forces with their strategic bombers. German dispositions, night of 24 -- 25 July 1944 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 ( Major General Manton S. Eddy ) and the 30th Infantry Division ( Major General Leland Hobbs ), which would break into the German defensive zone and then hold the flanks of the penetration while the 1st Infantry Division ( Major General Clarence Huebner ) and 2nd Armored Division ( Major General Edward H. Brooks ) 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 Armored Division armor that would move south toward Coutances ''. The 2nd Armored Division -- part of `` Collins ' exploitation force '' of the 2nd Armored Division in the east of the VII Corps sector and the `` 1st Infantry Division reinforced by Combat Command B ( CCB ) of the 3rd Armored 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 7,000 yd ( 6,400 m ) front, unlike previous American broad front offensives and would have a mass of air support. Fighter - bombers would concentrate on hitting forward German defenses in a 250 yd ( 230 m ) belt immediately south of the Saint - Lô -- Periers road, while General Spaatz 's heavy bombers would bomb to a depth of 2,500 yd ( 2,300 m ) behind the German main line of resistance. It was anticipated that the physical destruction and shock value of a short, intense preliminary bombardment would greatly weaken the German defense 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. armored vehicles could maneuver 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. Supporting operations Main articles : Operation Goodwood, Operation Atlantic, and Operation Spring Men of the 1st Battalion, Welsh Guards, part of the 32nd Guards Brigade of the Guards Armoured Division, in action near Cagny, 19 July 1944. 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 ( 5,400 t ) 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 armored 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 river 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 ( Royal Highland Regiment ) 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 armor 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 190 tanks now faced the First Army. Seven Panzer divisions with 750 tanks were around Caen, far away from Operation Cobra as were all the heavy Tiger tank battalions and the three Nebelwerfer brigades in Normandy. Logistics Each division consumed 750 short tons ( 680 t ) of supplies daily. Allied offensive Preliminary attacks 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 ( which had been in action since its D - Day defense of Omaha Beach ) 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 break - out 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. Main attack and breakthrough 25 -- 27 July 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 strongpoints and enemy artillery along a 300 yd ( 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 ( 5,500 m × 2,000 m ) 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. 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 Theater 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 armored 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 ( 3.46 in ) guns -- VII Corps gained only 2,200 yd ( 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 veteran 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 the 26th, Major General Troy H. Middleton 's VIII Corps entered the battle, led by the 8th and 90th Infantry Divisions. 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 ' advance. By noon on 27 July, the 9th Infantry Division of VII Corps was also clear of any organized German resistance, and was advancing rapidly. Breakout and advance 28 -- 31 July By 28 July, the German defenses across the U.S. front had largely collapsed under the full weight of VII and VIII Corps ' advance, and resistance was disorganised and patchy. VIII Corps ' 4th Armored Division -- 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 variously counterattacked by elements of the 2nd SS Panzer, 17th SS Panzergrenadier, and 353rd Infantry Divisions, all seeking to escape entrapment. A desperate counterattack was mounted against the 2nd Armored Division by German remnants, but this was a disaster and the Germans abandoned their vehicles and fled on foot. An exhausted and demoralized Bayerlein reported that his Panzer Lehr Division was `` finally annihilated '', with its armor wiped out, its personnel either casualties or missing, and all headquarters records lost. US M5A1 Stuart tank of the 4th Armored Division ( VIII Corps ) in Coutances Meanwhile, Marshal von Kluge -- commanding all German forces on the Western Front ( Oberbefehlshaber West ) -- was mustering reinforcements, and elements of the 2nd and 116th Panzer Divisions were approaching the battlefield. The U.S. XIX Corps -- led by Major General Charles H. Corlett -- 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 July near Saint - Denis - le - Gast, to the east of Coutances, elements of the U.S. 2nd Armored Division found themselves fighting for their lives against a German column from the 2nd SS Panzer and 17th SS Panzergrenadier Divisions, which passed through the American lines in the darkness. Other elements of the 2nd Armored were attacked near Cambry and fought for six hours ; however, Bradley and his commanders knew that they were currently dominating the battlefield and such desperate assaults were no threat to the overall American position. When ordered to concentrate his division, Colonel Heinz Günther Guderian -- 116th Division 's senior staff officer -- 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 successfully counterattack 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 Main article : Operation Bluecoat On 30 July, to protect Cobra 's flank and prevent the disengagement and relocation of further German forces, the British VIII Corps and XXX Corps launched Operation Bluecoat south 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 ( Operation Liège ), the German counter-offensive, 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 rearguard of the remaining armoured and motorised 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. Aftermath Map showing the breakout from the Normandy beachhead At noon on 1 August, the U.S. Third Army was activated under the command of Lieutenant General George S. Patton. Lieutenant General Courtney Hodges assumed command of the First Army and Bradley was promoted to the overall command of both armies, named the U.S. 12th Army Group. Patton wrote a poem containing the words, So let us do real fighting, boring in and gouging, biting. Let 's take a chance now that we have the ball. Let 's forget those fine firm bases in the dreary shell raked spaces, Let 's shoot the works and win ! Yes, win it all ! 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 German army in Normandy had been reduced to such a poor state by the Allied offensives that, with no prospect of reinforcement in the wake of 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 '' 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 between them. Hopelessly optimistic, the offensive threat 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. With von Kluge 's few remaining battleworthy formations destroyed by the First Army, the Allied commanders realised that the entire German position in Normandy was collapsing. Bradley declared : This is an opportunity that comes to a commander not more than once in a century. We 're about to destroy an entire hostile army and go all the way from here to the German border. 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 Armored 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 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. See also Normandy portal Footnotes Jump up ^ Of which 700 were from VIII Corps, and 600 from VII Corps, while the rest are from unknown specific other units. Jump up ^ `` The quick capture of that key city ( Caen ) and the neighbourhood of Carpiquet was the most ambitious, the most difficult and the most important task of Lieutenant - General J.T. Crocker 's I Corps ''. Wilmot states `` The objectives given to Crocker 's seaborne divisions were decidedly ambitious, since his troops were to land last, on the most exposed beaches, with the farthest to go, against what was potentially the greatest opposition. '' Jump up ^ These included the bulk of the available armored reserves : the 1st SS Panzer Division Leibstandarte SS Adolf Hitler, the 12th SS Panzer Division Hitlerjugend and the Panzer - Lehr - Division. Jump up ^ By 10 July, Bradley had become concerned enough to write that the Allies faced the possibility of a World War I - type stalemate in the campaign. Jump up ^ I Corps suffered 3,817 casualties and VIII Corps suffered 1,020 casualties. Jump up ^ Reynolds claims that a careful study of the relevant documents indicate a maximum tank loss of 253 tanks during Goodwood, most of which were repairable but Buckley claims 21st Army Group lost around 400 tanks during the operation, although he too notes that most were eventually recovered. Citations ^ Jump up to : Williams, p. 204 ^ Jump up to : Bercuson, p. 232 ^ Jump up to : Pugsley, p. 47 ^ Jump up to : Zaloga, p. 30 ^ Jump up to : Hastings, p. 236 ^ Jump up to : Jackson, p. 113 Jump up ^ Green, p. 62 Jump up ^ Pugsley, p. 53 Jump up ^ Stephen Napier, Armoured Campaign Jump up ^ Stephen Napier, Armoured Campaign ^ Jump up to : Trew, p. 64 Jump up ^ Van der Vat, p. 110 Jump up ^ Bradley, p. 261 Jump up ^ Williams, p. 24 Jump up ^ Williams, p. 38 Jump up ^ Ellis, p. 78 Jump up ^ Greiss, p. 308 Jump up ^ Ellis, p. 81 ^ Jump up to : Keegan, p. 135 Jump up ^ Ellis, p. 171 Jump up ^ Wilmot, p. 272 Jump up ^ Bercuson, p. 215 ^ Jump up to : Williams, p. 131 Jump up ^ Greiss, p. 317 Jump up ^ Greiss, p. 308 -- 310 Jump up ^ Williams, p. 114 ^ Jump up to : Williams, p. 163 ^ Jump up to : Greiss, p. 312 Jump up ^ Hastings, p. 163 Jump up ^ Hastings, p. 165 ^ Jump up to : Greiss, p. 316 ^ Jump up to : Hastings, p. 249 Jump up ^ Williams, p. 126 Jump up ^ Lewin, p. 336 Jump up ^ Esposito, pp. 78 -- 80. Jump up ^ Wilmot, p. 351 Jump up ^ Greiss, p. 311 ^ Jump up to : Trew, p. 49 Jump up ^ Blumenson, p. 187 Jump up ^ Zaloga, p. 32 Jump up ^ D'Este, p. 338 Jump up ^ Weigley, p. 136 Jump up ^ Pogue, p. 197 Jump up ^ Williams, p. 175 ^ Jump up to : Bradley, p. 272 Jump up ^ Zaloga, p. 7 ^ Jump up to : Hastings, p. 252 ^ Jump up to : Yenne, Bill ( 2004 ). Operation Cobra and the Great Offensive : Sixty Days that Changed the Course of World War II. New York : Simon & Schuster. p. 49. ISBN 978 - 1 - 4391 - 8263 - 5. Jump up ^ Zaloga, Steven J. ( 2004 ). Operation Cobra 1944 : Breakout from Normandy. Praeger. p. 44. ISBN 0 - 275 - 98263 - 7. Jump up ^ Hastings, p. 250 Jump up ^ Esposito, pp. 76 -- 77 ^ Jump up to : Williams, p. 185 ^ Jump up to : Hastings, pp. 249 -- 250 ^ Jump up to : Williams, p. 181 ^ Jump up to : Weigley, p. 151 Jump up ^ Griess, p. 324 Jump up ^ Blumenson, p. 219 Jump up ^ Zaloga, p. 3 Jump up ^ Weigley, p. 149 Jump up ^ Blumenson, p. 207 ^ Jump up to : Williams, p. 161 Jump up ^ Williams, p. 165 Jump up ^ Williams, p. 167 Jump up ^ Wilmot, p. 362 Jump up ^ Reynolds, p. 186 Jump up ^ Buckley, p. 36 Jump up ^ Trew, pp. 97 -- 98 Jump up ^ Van - Der - Vat, p. 158 ^ Jump up to : Copp, Approach to Verrières Ridge Jump up ^ Zuehlke, p. 166 Jump up ^ Stacey, pp. 195 -- 196 Jump up ^ Bercuson, p. 225 ^ Jump up to : Hastings, p. 256 Jump up ^ Wilmot, p. 389 Jump up ^ Clymer, Samuel ( August 2011 ). `` Operation Pluto : The Red Ball Express '' ( PDF ). The Intercom, Journal of the Cape Canaveral Chapter of the Military Officers Association of America. 34 ( 8 ) : 8. Archived from the original ( PDF ) on 26 December 2011. ^ Jump up to : Hastings, p. 253 Jump up ^ Williams, p. 174 Jump up ^ Williams, p. 180 ^ Jump up to : Hastings, p. 254 Jump up ^ Sullivan, p. 107 ^ Jump up to : Williams, p. 182 ^ Jump up to : Williams, p. 183 ^ Jump up to : Hastings, p. 255 ^ Jump up to : Hastings, p. 257 ^ Jump up to : Hastings, p. 258 ^ Jump up to : Hastings, p. 260 Jump up ^ Hastings, p. 261 ^ Jump up to : Hastings, p. 262 Jump up ^ Hastings, p. 263 Jump up ^ Hastings, p. 265 Jump up ^ Daglish 2009, p. 301. Jump up ^ Ellis 1962, pp. 419 -- 433. Jump up ^ Hastings, p. 266 Jump up ^ Williams, p. 186 Jump up ^ Wilmot, p. 399 Jump up ^ Hastings, p. 277 Jump up ^ D'Este, p. 414 ^ Jump up to : Williams, p. 196 Jump up ^ Wilmot, p. 401 Jump up ^ Hastings, p. 283 Jump up ^ Hastings, p. 285 Jump up ^ Hastings, p. 286 Jump up ^ Williams, p. 194 ^ Jump up to : Williams, p. 197 Jump up ^ Hastings, p. 301 Jump up ^ Williams, p. 203 Jump up ^ Hastings, p. 306 Jump up ^ Hastings, p. 313 References Bercuson, David ( 2004 ) ( 1996 ). Maple Leaf Against the Axis. Red Deer Press. ISBN 0 - 88995 - 305 - 8. Blumenson, M. ( 1961 ). Breakout and Pursuit ( PDF ). United States Army in World War II : European Theater of Operations. Washington, D.C. : US Government Printing Office. ISBN 978 - 0 - 16 - 001882 - 4. Retrieved 21 August 2016. Bradley, General of the Army Omar N. ( 1983 ). A General 's Life. Simon and Schuster. ISBN 0 - 671 - 41023 - 7. Buckley, John, ed. ( 2007 ) ( 2006 ). The Normandy Campaign 1944 : Sixty Years On. London : Routledge. ISBN 0 - 415 - 44942 - 1. Copp, Terry ( 1 March 1999 ). `` The Approach to Verrières Ridge ''. Legion Magazine. Ottawa : Canvet Publications ( 25 ). Retrieved 26 January 2009. Daglish, I. ( 2009 ). Operation Bluecoat. Pen & Sword. ISBN 0 - 85052 - 912 - 3. D'Este, Carlo. Decision in Normandy. Konecky & Konecky. ISBN 1 - 56852 - 260 - 6. Ellis, L.F. ( 2004 ) ( 1st pub. HMSO 1962 ). Victory in the West : The Battle of Normandy. History of the Second World War, United Kingdom Military Series. I ( facsimile ed. ). Uckfield : Naval & Military Press. ISBN 1 - 845740 - 58 - 0. Esposito, Brigadier General Vincent ( 1995 ). World War II : European Theater. The West Point Atlas of War. Tess Press. ISBN 1 - 60376 - 023 - 7. Green, Michael ( 1999 ). Patton and the Battle of the Bulge : Operation Cobra and Beyond. MBI. ISBN 0 - 7603 - 0652 - 4. Griess, Thomas ( 2002 ). The Second World War : Europe and the Mediterranean ( SquareOne ed. ). West Point, New York : Department of History, United States Military Academy. ISBN 0 - 7570 - 0160 - 2. Hastings, Max ( 2006 ) ( 1985 ). Overlord : D - Day and the Battle for Normandy ( repr. ed. ). Vintage Books USA. ISBN 0 - 307 - 27571 - X. Jackson, G.S. ( 2006 ) ( 1945 ). 8 Corps : Normandy to the Baltic. Staff, 8 Corps. MLRS Books. ISBN 978 - 1 - 905696 - 25 - 3. Keegan, John ( 2006 ). Atlas of World War II. Collins. ISBN 0 - 06 - 089077 - 0. Lewin, Ronald ( 2001 ) ( 1978 ). Ultra goes to War ( Penguin Classic Military History ed. ). London : Penguin Group. ISBN 978 - 0 - 14 - 139042 - 0. Napier, Stephen ( 2015 ). Armoured Campaign in Normandy June - August 1944. The History Press. ISBN 0750962704. Pogue, Forrest C. ( 1954 ). The Supreme Command. United States Government Printing Office. ISBN 0 - 16 - 001916 - 8. Pugsley, Christopher ( 2005 ). Operation Cobra. Battle Zone Normandy. Sutton. ISBN 0 - 7509 - 3015 - 2. Reynolds, Michael ( 2002 ). Sons of the Reich : The History of II SS Panzer Corps in Normandy, Arnhem, the Ardennes and on the Eastern Front. Casemate Publishers and Book Distributors. ISBN 0 - 9711709 - 3 - 2. Stacey, Colonel Charles Perry ; Bond, Major C.C.J. ( 1960 ). `` The Victory Campaign : The operations in North - West Europe 1944 -- 1945 '' ( PDF ). Official History of the Canadian Army in the Second World War. The Queen 's Printer and Controller of Stationery Ottawa. OCLC 155106767. Archived from the original ( PDF ) on 12 September 2008. Retrieved 2008 - 08 - 20. Sullivan, John J. ( 1988 ). `` The Botched Air Support of Operation Cobra '' ( PDF ). Parameters, the US Army 's Senior Professional Journal. 18 ( March ) : 97 -- 110. Retrieved 28 November 2010. Trew, Simon ; Badsey, Stephen ( 2004 ). Battle for Caen. Battle Zone Normandy. The History Press. ISBN 0 - 7509 - 3010 - 1. Van Der Vat, Dan ( 2003 ). D - Day : The Greatest Invasion : A People 's History. Madison Press. ISBN 1 - 55192 - 586 - 9. Weigley, Russell ( 1981 ). Eisenhower 's Lieutenants. Indiana University Press. ISBN 0 - 253 - 13333 - 5. Williams, Andrew ( 2004 ). D - Day to Berlin. Hodder. ISBN 0 - 340 - 83397 - 1. Wilmot, Chester ; Christopher Daniel McDevitt ( 1997 ) ( 1952 ). The Struggle for Europe. Wordsworth Editions. ISBN 1 - 85326 - 677 - 9. Zaloga, Steven J. ( 2001 ). Operation Cobra 1944 : Breakout from Normandy. Osprey. ISBN 1 - 84176 - 296 - 2. Zuehlke, Mark ( 2001 ). The Canadian Military Atlas. Stoddart. ISBN 0 - 7737 - 3289 - 6. External links Normandiememoire.com. `` Operation Cobra : the break - out ''. Archived from the original on 21 August 2003. Wiacek, Jacques. `` Operation Cobra and final stages of the battle in normandy ''. Youtube. `` The Big Picture, BREAKOUT AND PURSUIT 1961, Operation Cobra ''. World War II Asia and the Pacific China South - East Asia North and Central Pacific South - West Pacific Europe Western Eastern Mediterranean and Middle East North Africa East Africa Italy West Africa Atlantic North America South America Casualties Military engagements Conferences Commanders Participants Allies ( leaders ) Australia Belgium Brazil Canada China Cuba Czechoslovakia Denmark Ethiopia France Free France ( from June 1940 ) Greece India Italy ( from September 1943 ) Luxembourg Mexico Netherlands New Zealand Norway Philippines ( Commonwealth ) Poland South Africa Southern Rhodesia Soviet Union United Kingdom United States Puerto Rico Yugoslavia Axis and Axis - aligned ( leaders ) Albania Bulgaria Reorganized National Government of the Republic of China Independent State of Croatia Finland Germany Hungary Free India Iraq Italy ( until September 1943 ) Italian Social Republic Japan Manchukuo Philippines ( Second Republic ) Romania Slovakia Thailand Vichy France Armed neutrality Resistance Albania Austria Belgium Bulgaria Czech lands Denmark Estonia Ethiopia France Germany Greece Hong Kong Italy Japan Jewish Korea Latvia Lithuania Luxembourg Malaya Netherlands Northeast China Norway Philippines Poland Anti-communist Romania Thailand Soviet Union Slovakia Western Ukraine Vietnam Yugoslavia Monarchists Timeline Prelude Africa Asia Europe 1939 Poland Phoney War Winter War Atlantic Changsha China 1940 Weserübung Netherlands Belgium France Armistice of 22 June 1940 Britain North Africa West Africa British Somaliland North China Baltic States Moldova Indochina Greece Compass 1941 East Africa Yugoslavia Shanggao Greece Crete Iraq Soviet Union ( Barbarossa ) Finland Lithuania Syria and Lebanon Kiev Iran Leningrad Moscow Sevastopol Pearl Harbor The outbreak of the Pacific War Hong Kong Philippines Changsha Malaya Borneo ( 1941 -- 42 ) 1942 Burma Changsha Java Sea Coral Sea Gazala Dutch Harbor Attu ( occupation ) Kiska Zhejiang - Jiangxi Midway Rzhev Blue Stalingrad Singapore Dieppe El Alamein Guadalcanal Torch 1943 Tunisia Kursk Smolensk Solomon Islands Attu Sicily Cottage Lower Dnieper Italy Armistice of Cassibile Gilbert and Marshall Islands Burma Northern Burma and Western Yunnan Changde 1944 Monte Cassino / Shingle Narva Korsun -- Cherkassy Tempest Ichi - Go Overlord Neptune Normandy Mariana and Palau Bagration Western Ukraine Tannenberg Line Warsaw Eastern Romania Belgrade Paris Dragoon Gothic Line Market Garden Estonia Crossbow Pointblank Lapland Hungary Leyte Ardennes Bodenplatte Philippines ( 1944 -- 1945 ) Burma ( 1944 -- 45 ) 1945 Vistula -- Oder Iwo Jima Western invasion of Germany Okinawa Italy ( Spring 1945 ) Borneo Syrmian Front Berlin Czechoslovakia Budapest West Hunan Guangxi Surrender of Germany Project Hula Manchuria Manila Borneo Taipei Atomic bombings Debate Kuril Islands Shumshu Surrender of Japan End of World War II in Asia Aspects General Famines Bengal famine of 1943 Chinese famine of 1942 -- 43 Greek Famine of 1941 - 1944 Dutch famine of 1944 -- 45 Vietnamese Famine of 1945 Air warfare of World War II Blitzkrieg Comparative military ranks Cryptography Diplomacy Home front United States Australian United Kingdom Lend - Lease Manhattan Project Military awards Military equipment Military production Nazi plunder Opposition Technology Allied cooperation Total war Strategic bombing Puppet states Women Art and World War II Aftermath Expulsion of Germans Operation Paperclip Operation Osoaviakhim Operation Keelhaul Occupation of Germany Territorial changes of Germany Soviet occupations Romania Poland Hungary Baltic States Occupation of Japan First Indochina War Indonesian National Revolution Cold War Decolonization Treaty on the Final Settlement with Respect to Germany Popular culture War crimes Allied war crimes Soviet war crimes British war crimes United States war crimes German ( Forced labour ) / Wehrmacht war crimes Holocaust Aftermath Response Prosecution Italian war crimes Japanese war crimes Unit 731 Prosecution Croatian war crimes against the Serbs against the Jews Romanian war crimes Wartime sexual violence German military brothels Camp brothels Rape during the occupation of Japan Sook Ching Comfort women Rape of Nanking Rape of Manila Rape during the occupation of Germany Rape during the liberation of France Rape during the liberation of Poland Prisoners Finnish prisoners of war in the Soviet Union German prisoners of war in the Soviet Union German prisoners of war in the United States Italian prisoners of war in the Soviet Union Japanese prisoners of war in the Soviet Union Japanese prisoners of war in World War II German mistreatment of Soviet prisoners of war Polish prisoners of war in the Soviet Union Romanian prisoners of war in the Soviet Union Bibliography Portal Primary articles on the Battle of Normandy, Western Front, World War II Operations Locations See also Operation Overlord ( The overall invasion plan ) Operation Neptune ( The assault plan ) American airborne landings in Normandy Operation Deadstick ( UK 6th Airborne ) Operation Tonga ( UK 6th Airborne ) Battle of Merville Gun Battery ( UK 6th Airborne ) Operation Mallard ( UK 6th Airborne ) Battle of Bréville ( UK 6th Airborne ) Operation Pluto ( Pipe - Line Under The Ocean ) Operation Fortitude ( Deception plan ) Operation Perch ( UK ) Operation Martlet ( UK ) Operation Epsom ( UK ) Operation Windsor ( Canada ) Operation Charnwood ( UK ) Operation Jupiter ( UK ) Operations Greenline, Pomegranate and Express ( UK ) Operation Goodwood ( UK ) Operation Atlantic ( Canada ) Operation Spring ( Canada ) Operation Cobra ( US ) Operation Bluecoat ( UK ) Operation Totalize ( Canada, Poland, UK ) Operation Lüttich ( German ) Operation Tractable ( Canada, Poland, UK ) Battle for Brest ( US ) Battle for Caen ( UK, Canada ) Battle of Verriéres Ridge ( Canada ) Battle of Carentan ( US ) Battle of Cherbourg ( US ) Battle of Villers - Bocage ( UK ) Landing points ( W → E ) : Utah Beach ( US ) Omaha Beach ( US ) Pointe du Hoc ( US ) Gold Beach ( UK ) Juno Beach ( Canada ) Sword Beach ( UK ) Other : Crisbecq Battery Falaise Pocket Hill 262 Hillman Fortress Houlgate battery Longues - sur - Mer battery Maisy battery Merville Gun Battery Mont Canisy battery Pegasus Bridge Category : Operation Overlord Category : Operation Overlord people Atlantic Wall D - Day Dieppe Raid Hobart 's Funnies Rhino tank Allied forces in Normandy Mulberry harbour Liberation of Paris ( France ) Operation Dragoon ( France, UK, US ) Operation Jedburgh ( France, UK, US ) Normandy US Cemetery & Memorial Brittany US Cemetery & Memorial More information on Battle of Normandy : D - day from Wiktionary D - day Textbooks from Wikibooks D - day Quotations from Wikiquote D - day Source texts from Wikisource D - day Images and media from Commons D - day from Wikinews Retrieved from `` https://en.wikipedia.org/w/index.php?title=Operation_Cobra&oldid=802173162 '' Categories : 1944 in France Battles and operations of World War II involving the United States Military operations of World War II involving Germany Operation Overlord Hidden categories : Use dmy dates from July 2013 Coordinates on Wikidata Featured articles Talk Contents About Wikipedia Български Čeština Dansk Deutsch Español Français Italiano עברית Nederlands 日本 語 Norsk Polski Português Română Русский Slovenščina Svenska தமிழ் Türkçe Українська 中文 Edit links This page was last edited on 24 September 2017, at 13 : 00. 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Question: when did the allies break out of normandy
Answer: 25–31 July 1944