The first fighter dove to the attack at 9:38 a.m. on 25 July, and the last bomber pulled away at 12:23 p.m. In the three hours between, the areas were smothered with almost 4,200 tons of bombs, and struck repeatedly by rockets, machine gun and cannon fire, and some napalm. More than 1,500 heavies had dropped, in addition to 380 medium bombers and 559 fighters.
Some bombing was very inaccurate, and US forces took casualties. One German panzer division was shattered; those not immediately killed or wounded were deafened, in shock, and demoralized completely. Cobra had won the battle of St-Lo, but Eisenhower said it should not be done again because of the inherent possibility of friendly casualties.
Air and armored units set up a team approach, with pilots attached to ground units to call in attacks according to immediate tactical needs. Armored column cover became a new operational mission, wherein four aircraft per column of advancing armored troops flew armed reconnaissance and protected the column.
The Ninth AF, fully geared to its primary task of ground support, bombed and strafed the retreating Germans. On 29 July, they caught a boxed-in German armored force on a road between two small French villages. From mid-afternoon to late in the summer evening, P-47s of the 405th Fighter-Bomber Group systematically smashed the 3-mile (4.8-km) long column. They were aided by artillery and tank gunfire from ground forces blocking both ends of the road. It was devastating; the road was made impassable. The attack destroyed 66 tanks, 204 vehicles and 11 guns, and damaged 56 tanks and 55 vehicles which were abandoned.