On the bombardment of Caen as part of Operation Overlord ...
This planned offensive became increasingly necessary once the euphoria surrounding D-Day had worn off ... politicians and the military on both sides of the Atlantic wished to see the campaign move on.
The response of the land commander - Montgomery - was to order a direct assault on Caen. This was known as Operation Charnwood, and in the course of the operation the city was reduced to rubble by bombing raids. Canadian troops then struggled through its streets, and by 10 July, when the attack ended, they had penetrated as far as the river Orne.
Excerpt from Operation Overlord: D-Day to Paris by Lloyd Clark