In response to a request from the French government for the provision of ten fighter squadrons to provide air support, Air Chief Marshal Sir Hugh Dowding, Commander-in-Chief of RAF Fighter Command, insisted that this number would deplete British defences severely, and so initially only four squadrons of Hurricanes, 1, 73, 85 and 87, were relocated to France, keeping Spitfires back for "Home" defence. The first to arrive was No.73 Squadron on 10 September 1939, followed shortly by the other three. A little later, 607 and 615 Squadrons joined them.