Supplying the army in full became an impossibility. The lack of grass and feed weakened the remaining horses, almost all of which died or were killed for food by starving soldiers. Without horses, the French cavalry ceased to exist; cavalrymen had to march on foot. Lack of horses meant many cannons and wagons had to be abandoned. Much of the artillery lost was replaced in 1813, but the loss of thousands of wagons and trained horses weakened Napoleon's armies for the remainder of his wars. Starvation and disease took their toll, and desertion soared. Many of the deserters were taken prisoner or killed by Russian peasants. Badly weakened by these circumstances, the French military position collapsed. Further, defeats were inflicted on elements of the Grande Armée at Vyazma, Polotsk and Krasny. The crossing of the river Berezina was a final French calamity; two Russian armies inflicted heavy casualties on the remnants of the Grande Armée as it struggled to escape across improvised bridges.