Battle
A local breakthrough becomes an encirclement manoeuvre; the exit initially remains open
Military history
This dossier treats Cobra–Falaise as a deliberate operational arc, not a single battle fought at one point. Bombardment and the breakthrough west of Saint-Lô dislocated the German front; the breakout through Avranches opened depth; the German attack at Mortain committed armoured forces to an operation that failed; Allied drives from north and south converged on Falaise, Argentan, Trun, and Chambois. The pocket was finally closed, but late enough for some German forces to escape, often without their heavy equipment. Units on the map are therefore phase groupings, not georeferenced battalion positions.
The sequence begins with the bocage deadlock and follows the conversion of a breakthrough into encirclement. Cobra, Avranches, Mortain, and Falaise were not four independent episodes: each stage changed the depth, roads, and placement of reserves. This continuity explains why the dossier retains the dates 25 July to 21 August.
On 25 July, a massive bombardment struck the German position west of Saint-Lô. The sources attest broken communications and a moral shock, but also bombing errors and continued resistance on the ground. The breach became operational only when infantry and armour exploited the window toward Coutances and then Avranches.
Taking Avranches and activating Third Army gave the Allies new depth, but the Avranches corridor remained narrow and road-dependent. The Mortain offensive targeted precisely this hinge. Its failure, under the combined effect of ground resistance and air support, left German armoured forces exposed within the encirclement manoeuvre.
In the north, Anglo-Canadian attacks advanced slowly toward Falaise; in the south, XV Corps and American and French formations reached Argentan. The two jaws did not meet immediately: the Trun–Chambois bottleneck remained passable for some German forces until the fighting of 19–21 August. The exact closure date varies depending on whether it means contact, tactical sealing, or elimination of the pocket.
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Military history
HTML chapter 4, lignes 25–40 pour le plan et le bombardement de Cobra, lignes 52–70 pour VII et VIII Corps, Coutances et la progression des 25–28 juillet, lignes 88–105 pour la Third Army, Avranches et Vire ; rapport imprimé, pp.35–41, carte 3 p.37.
Breakthrough plan, bombardment volumes, corps composition, breakout toward Coutances and Avranches, activation of Third Army, and the operational change of scale.
View ↗HTML chapter 5, lignes 10–35 pour Mortain et la décision d'encerclement, lignes 37–48 pour Falaise, Argentan et les deux lèvres, lignes 52–61 pour les échappées, le corridor de Trun et les dates de fermeture ; rapport imprimé, pp.42–45, carte 4 p.44.
Operational chronology of Mortain, XV Corps' pivot toward Argentan, Canadian advance toward Falaise, German strategy of the lips, and cautious description of forces escaped or trapped.
View ↗PDF officiel, pagination imprimée pp. 203–226, chapitre IX : Situation at 1 August, Planning the Breakout Attack, Air Support for Totalize et les deux phases de Totalize ; cartes et croquis 13–15.
Allied command structure, the Caen front's fixing role, and preparation of the drive toward Falaise.
View ↗PDF officiel, pagination imprimée pp. 245–250 pour la prise de Falaise et son dernier point nettoyé vers 2 h le 18 ; pp. 252–265 pour Trun, St-Lambert et Chambois, surtout pp. 256–264 pour le contact, les échappées, la fermeture du 21 et les 3 043 véhicules motorisés et canons ; note p. 265 sur les 1 270 véhicules du relevé élargi incomplet ; carte 5 p. 266.
Capture and clearing of Falaise, movements toward Trun, St-Lambert, and Chambois, dispute over the taking of Chambois, escapes on 20 August, Canadian closure date of 21 August, and distinct scopes of equipment surveys.
View ↗HTML chapter IV, lignes 24–42 pour Cobra, Avranches et la pression sur Caen, lignes 63–92 pour le plan de Totalize et les transports d'infanterie, lignes 106–124 pour les colonnes de l'attaque du 7–8 août ; imprimé pp.103–112.
Relationship between the American breakthrough and Canadian drive, preparation of Totalize, armour–infantry integration, and effect of fortified terrain.
View ↗HTML, pp.29–31, lignes 393–406 pour le lien entre bombardement, action terrestre et échappées, lignes 409–424 pour le calendrier ULTRA et la réfutation du mythe d'un avertissement complet ; carte Mortain Counterattack, p.31.
Effects and limits of air strikes, distinction between claims and ground results, bounded role of intelligence at Mortain, and combined action in the pocket.
View ↗PDF officiel : chapitres XI–XIII, pp.197–262 pour les préparatifs, le bombardement et la rupture de Cobra ; chapitre The Mortain Counterattack, p.457 et suivantes ; chapitre The Argentan-Falaise Pocket, p.506 et carte p.513 ; chapitre Closing the Pocket, p.528.
Cross-check of the American sequence, German reactions, change of scale among breakthrough, Mortain, and pocket; control on the limits of pursuit.
View ↗Military Review, mars–avril 2022, sections « Exploiting Cobra » et « Ultra » : activation de la Third Army et corridor d'Avranches ; paragraphes commençant « On the night of 6 August » et « On 7 August » pour les interceptions reçues par Patton, les trois divisions retenues près de Saint-Hilaire, Lüttich, le rôle du VII Corps et le pivot du XV Corps ; figure 2 pour la situation du 14 août.
Distinguishing the absence of complete tactical preparation at Mortain from the use of ULTRA at Third Army scale; cross-checking the Avranches breakout, XV Corps' change of axis, and exploitation decisions.
View ↗C. P. Stacey, The Victory Campaign, chapitre X, PDF officiel, pagination imprimée pp. 254–255 : lettre de Kluge et jugement sur l'offensive vers Avranches, puis ordres de Model et Hausser sur les deux murs de la poche.
Contemporary testimony on the impossibility of the offensive and the forced shift to extraction; the quotation is retained as a reproduced document, distinct from a neutral narrative of the whole battle.
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