Answer: they didn't
Step-by-step explanation:
Most of the men in Napoleon’s Grand Armée were conscripts drawn from the poorer classes. Every able-bodied man of age in France was expected to willingly join the ranks to defend the Republic – or risk losing citizenship. In theory soldiers were eligible for discharge after five years, but after 1804, most discharges were only for medical reasons. Most new soldiers received little training, and had to learn their trade on the battlefield.
Supplies were usually scarce, since Napoleon’s armies traveled with small logistical trains to improve mobility. Uniforms were often ill-fitting and uncomfortable. Boots rarely lasted more than a few weeks. Soldiers learned by experience that marauding was often a more reliable source of food, horses and other provisions than the army’s supply system. Often hungry and eager to fight for the glory of France and their emperor, Napoleon’s soldiers were the most feared force in Europe.