This book covers the British/Canadian offensive to close the Falaise Pocket. After D-Day, the Allies were in a pocket surrounded by German troops and the ocean, and pretty much stuck in Normandy. The Wehrmacht, thinking the British forces in the north part of the pocket to be more likely to go on the offensive, moved their spare forces north to block a breakout.
The Allies were planning dual offenses in late July, having brought reinforcements in across the beaches and through the ports they held. Bad weather postponed these until Operation Cobra, the attack by the Americans in the south began. Cobra effectively destroyed the German defenses in the south, but left the center and northern forces intact.
The armored force continued to advance, and began to encircle the German forces opposite the center.