Napoleon's France

Napoleon’s Grande Armée was a highly mobile, merit-based force built around independent corps d’armée (infantry, cavalry, and massed artillery) that could march separately, concentrate fast, and smash enemies with aggressive maneuver and firepower.
Fueled by conscription and rigorous drilling, it reached enormous sizes, but chronic supply strains and overreach—especially in Spain and the 1812 Russia campaign—ultimately bled it dry.