The 29th Infantry Division attacked to seize Vire, a town overlooking converging roads now vital to the offensive.
The Germans defended with roadblocks covered by antitank guns, and had good positions on dominating ground.
The division switched from leading with tanks to leading with infantry as the terrain thickened.
These secured high ground west of Vire, and then swept into the town relying upon underbrush, outcroppings and ravines to cover their approach.
After house-to-house fighting, they secured Vire on 7 August.
Other American divisions had sped past Avranches and pushed deep into Brittany, and still others had hooked eastwards towards Argentan and Le Mans.
Fearing encirclement, the Germans attempted a desperate counterattack through Mortain to recapture Avranches and cut off the advancing American spearheads.
Meanwhile the 29th Infantry Division pushed on for some distance southeast of Vire, and on 13 August shifted its axis northeast towards Tinchebray.