On the 24th of July 1944, the German forces around St Lo, in Normandy, did not have a clue about the hell that was about to be unleashed upon them. Their dispositions looked like this:

Source; http://www.dean.usma.edu/history/web03/atlases/AtlasesTableOfContents.html

To the west of St Lo, you can see the area that the Americans chose to breakout from the close hedgerow fighting that had so favoured the Germans for the months of June and July 1944.

Source; http://www.dean.usma.edu/history/web03/atlases/AtlasesTableOfContents.html

The Allies delivered a devastating aerial bombardment on the German front lines in the area on 25 July 1944. The line did not immediately give way. This was due to the American infantry not pushing quickly at first. Who could blame them? They had just spent 2 months fighting in the hedgerows and had learned to be cautious. Additionally, the lingering shock of the bombardment, which also killed and wounded several hundred Americans was still wearing off.
However, the American Commander on the ground, General J. Lawton Collins, saw no need to delay and committed his exploitation forces on the morning of the 26th. This was risky, because if the Germans had managed to slow down the attack further, it would have meant an American traffic jam right on the front lines. Luckily, they couldn't and the Americans pushed right through and found the German line disintegrating like it had not done for the Americans before in Normandy.
Thus began the great race from the beachheads to the German frontier that occurred over the next 2 months, including the liberation of Paris and most of the rest of France.

I rode through the breakout zone recently and below is some video of a wonderfully twisty ride I took from Gavray towards Avranches. This area was liberated around 28-30 July.

Normandy Breakout from TJ on Vimeo.

Ride Recommendation

Check out the Terre Liberte' route of Cobra- La Percee (the Breakout). The video above is from this route and starts in Gavray which is about half way in between Coutances and Avranches. Here's a Google map of the stretch of road on the video.

Book and Map Recommendations