Montebourg was situated along the main road to Cherbourg, a crucial target of the Allied advance. The Germans fortified the route and the Allied navy bombarded the town to weaken German defenses. Antony Beevor mentions this in his book D-Day: "But the town of Montebourg itself suffered badly on that Wednesday afternoon [June 7, 1944] as naval shells exploded, setting fire to a number of shops. In the main square, the Statue of joan d-Arc remained undamaged when all the buildings around were smashed." page 160.
You can see more photos of WWII Montebourg on "PhotosNormandie's" photostream on flickr.com