Lt Gen Omar Bradley (left), Commanding General, U.S. First Army, listens as Maj Gen J. Lawton Collins, Commanding General, US VII Corps, describes how the city of Cherbourg was taken. (c. June 1944)
On June 10, General Bradley and his staff debarked to establish a headquarters ashore. During Operation Overlord, he commanded three corps directed at the two American invasion targets, Utah Beach and Omaha Beach. During July he inspected the modifications made by Curtis G. Culin to Sherman tanks, that led to the Rhino tank. Later in July, he planned Operation Cobra, the beginning of the breakout from the Normandy beachhead. Operation Cobra called for the use of strategic bombers using huge bomb loads to attack German defensive lines. After several postponements due to weather, the operation began on July 25, 1944 with a short, very intensive bombardment with lighter explosives, designed so as not to create more rubble and craters that would slow Allied progress. Bradley was horrified when 77 planes bombed short and dropped bombs on their own troops, including General Lesley J. McNair
The ground belched, shook and spewed dirt to the sky. Scores of our troops were hit, their bodies flung from slit trenches. Doughboys were dazed and frightened....A bomb landed squarely on McNair in a slit trench and threw his body sixty feet and mangled it beyond recognition except for the three stars on his collar.
However, the bombing was successful in knocking out the enemy communication system, rendering German troops confused and ineffective, and opened the way for the ground offensive by attacking infantry. Bradley sent in three infantry divisions—the 9th, 4th and 30th—to move in close behind the bombing. The infantry succeeded in cracking the German defenses, opening the way for advances by armored forces commanded by Patton to sweep around the German lines.
As the build-up continued in Normandy, the Third Army was formed under Patton, Bradley's former commander, while General Hodges succeeded Bradley in command of the First Army; together, they made up Bradley's new command, the 12th Army Group. By August, the 12th Army Group had swollen to over 900,000 men and ultimately consisted of four field armies. It was the largest group of American soldiers to ever serve under one field commander.