For nearly a month, the Americans had been bogged down in the hellish war of the hedgerows. Operation Cobra, launched at the end of July, would at long last open a decisive gap in the German lines. General Bradley, commanding the First Army, had worked out his strategy extremely carefully. Aerial saturation bombing over a limited area would briefly destroy all the defences there and create a breach through which his forces could pour. The area he chose lay between the villages of La Chapelle-Enjuger and Hébécrevon, a few kilometres north of the main road between Saint-Lô and Coutances.

An initial attempt, on July 24th, proved disastrous, as the bombers dropped some of their projectiles on the American front lines, killing or wounding 150 men. Despite this, a second attempt was made the very next day. For three hours, 1,500 B-17 and B-24 bombers pummelled the target, supported by medium bombers and fighter bombers attacking with napalm. This time, the Germans did not escape so lightly. General Bayerlein’s Panzer Lehr, which had only recently arrived in the sector, was literally blown to pieces. 45-tonne Panther tanks were lifted off the ground by the force of the explosions and torn apart like children’s toys. Infantrymen were buried alive in their shelters. The few, shell-shocked survivors either surrendered without a fight or fled.

Even so, it was certainly no picnic for the American infantry. Fierce fighting continued throughout the 25th, as efforts were made to open up a passage for the armoured vehicles. Now that they had been fitted with the famous hedge-cutting devices invented by Sergeant Cullins, the American tanks were able to rip their way through the thickets with the greatest of ease.

On July 26th, Collins’ VII Corps advanced ten kilometres, taking first Saint-Gilles, then Canisy, after crossing the Coutances-Saint-Lô road. Cracks started to appear in the German front, reduced to a thin crust. It collapsed the next day. The American armoured divisions swept southwards and westwards. Marigny, Lessay and Périers were taken the same day. Coutances was liberated on the 28th by General Wood’s 4th Armoured Division.

Entire German units were encircled ‑ in the Roncey Pocket, for instance ‑, while others simply fell apart. The suffering they had endured during the previous two months of hard fighting suddenly came home to these shaken and demoralized troops. Thousands of men were captured, disarmed and, more often than not, left where they were, as there was no time to take them to a camp. Von Choltitz, the commander of the 84th Corps, vainly attempted to rebuild new lines of defence, but these became obsolete before they had even been established. Nothing could stop the Americans now.

On July 30th, Grow’s 6th Armoured Division crossed Bréhal and drove past Granville without stopping. Wood, who was still spearheading the advance, captured Avranches the same evening, and the next day succeeded in securing a vital bridgehead over the Sélune at Pontaubault bridge. The Americans were now in Brittany. In less than a week, Bradley’s troops had made a breakthrough of sixty kilometres and taken 18,000 prisoners. The stalemate had come to an end and the war of attrition had suddenly and dramatically been replaced by a war of movement.