As to the efficiency of the withdrawal I quote Macdonald again:
'It was said afterwards that, even had the bridge remained intact, we could not have made use of it, as it and the approaches to it were blocked by artillery and wagons. That may have been so, but at least the infantry might have attempted to cross, the cavalry would have abandoned their horses, and thus many lives might have been saved. The block arose from the fact that no supervision had been exercised, no orders given to keep this passage clear. Two strings of carriages were passing to the right and the left of the boulevards of Leipzic, a third along the principal street of the town; all three met at the head of the bridge, and it was a struggle which should get across first; the carriages caught each others wheels, blocked up the space, and our unhappy fate was decided.'
And he also wrote:
'I do not yet know by what name to call this criminal indifference: whether incapability, cowardice, or absence of all feeling, of all regret at the sacrifice of so many lives.'
Macdonald had not been with the main army in Russia of course, or this wouldn't have been such a shock to him.