At the beginning of September 1940, Sperrle could muster 350 serviceable bombers and dive-bombers and about 100 fighters, either for his own purposes or to support the 9th Army and, if necessary, the 6th Army in a landing. Sperrle lost Richthofen to Kesselring who took possession of some units in Normandy, and concentrated the available dive-bomber force near the Straits of Dover. Sperrle was sceptical about Fighter Command's reported losses. He had seen inflated claims made before in Spain, and advocated maintaining attacks on the RAF and the infrastructure supporting it. This strategy was about to change.