After a slow start reminiscent of the previous month's stalemate, the German line finally broke under General George Patton's assault, and on July 30 the Americans entered the town of Avranches at the bottom end of the Cotentin Peninsula. South and west of Avranches the countryside was open, ideal for tanks. Patton poured the VIII and XV Corps through the narrow passage (Germans still being dug in east of Avranches), corps and division commanders personally directing traffic at times.
The 6th Armored Division went northwest to capture St Malo and Brest, while the 4th Armored Division went south to Rennes and St Nazaire. Initially, this was Patton's sole mission, but on August 3 he made a momentous decision to leave only minimal forces to mop up Brittany and move everything else to the east as quickly as possible.
The German 7th Army counterattacked at the small town of Mortain on the night of August 6, but units of the 3rd Army were already east of it, and continued to press on. By August 16 the 1st Army had closed on Argentan, while the British had captured Falaise just to the north. Although the Germans began frantically withdrawing from the "Falaise Pocket", the Americans and British met on August 19, killing about 10,000 Germans and taking some 50,000 prisoner.
On the same day elements of 3rd Army reached the Seine, and on August 25 Paris was liberated. By August 31 the Meuse River and the Marne River had been crossed. At this point the supply lines were stretched very thin, and the primary limit to progress was fuel for the tanks.
(to be continued)