The plan was based those of Air Marshal Tedder and the "Overlord air plan" of Air Chief Marshal Leigh-Mallory, The plan was devised by Professor Solly Zuckermann, an advisor to the Air Ministry, to destroy transportation in Occupied France during the "preparatory period" for Operation Overlord so Germany would be unable to respond effectively to the invasion. The air campaign, carried out by the bombers of the RAF and USAAF crippled the German rail networks in France and played a crucial role in disrupting German reinforcements to the invasion area.