Sperrle and Kesselring objected to the halt order during the Battle of Dunkirk. Neither man believed the pocket could be reduced by air power alone. Sperrle, according to Richthofen, was ambivalent and had made few provisions for an attack on the port, preferring to concentrate on his area of operations in the south. Richthofen and Kesselring argued their commands had suffered heavy losses and were in no position to gain air superiority. The campaign began promisingly when Grauert and Loerzer assisted in the bombing and destruction of the inner harbour forcing Allied shipping to use the poorer outer harbour. On 26 May, the chiefs of staff of I., II., V. and VIII. "Fliegerkorps" met at Château de Roumont, near Ochamps, with Sperrle for a conference on coordination issues. ULTRA at Bletchley Park intercepted Richthofen's signals and ten aircraft were dispatched to bomb the building, which was hit but caused little damage.