March discipline and traffic control were not French specialties at any time.
The withdrawal was proceeding well until the bridge blew prematurely, however. It was the bridge destruction and the trapping of the French rear guard elements that turned Leipzig into a definite defeat instead of an excellent defensive action and withdrawal.
The loss of 30,000 prisoners, which included 15,000 already in hospitals (in addition to at least 38,000 killed and wounded), was what tipped the scales as to the severity of the defeat. Allied losses were in excess of 52,000.