as the russian dragons made their own first pass , carrying heavy loads of bombs meant for the french infantry positions , the raised artillery began to roar : canister-shot , filling the air with smoke and the flying balls and scraps of metal , and even though these nearly all fell harmlessly into the field between the armies , the hail barred an approach to the french forces from more than half the sky : only the center , where the french dragons were massed , was open air .