Three factors defeated us in the West where I was in command. First, the unheard-of superiority of your air force, which made all movement in daytime impossible. Second, the lack of motor fuel - oil and gas - so that the Panzers and even the Luftwaffe were unable to move. Third, the systematic destruction of all railway communications so that it was impossible to bring one single railroad train across the Rhine.

Quoted in "The Battle of the Bulge: Hitler's Final Gamble" - by Patrick Delaforce - History