The country was relatively poor but Napoleon demanded heavy taxes and payments and conscripted soldiers. Few of the men who marched into Russia with Napoleon in 1812 ever returned. The Kingdom was bankrupt by 1812. When Napoleon was retreating in the face of Allied advances in 1813, the Kingdom was overrun by the Allies and (in 1815) most of its territories became Prussian. Most of the reforms, however, remained in place.