In 1806, Napoleon issued the series of Berlin Decrees, which brought into effect the Continental System. This policy aimed to eliminate the threat from Britain by closing French-controlled territory to its trade. Britain maintained a standing army of just 220,000 at the height of the Napoleonic Wars, whereas France's strength peaked at over 2,500,000, as well as several hundred thousand national guardsmen that Napoleon could draft into the military if necessary; however, British subsidies paid for a large proportion of the soldiers deployed by other coalition powers, peaking at about 450,000 in 1813.
http://en.wikipedia.org/wiki/Napoleonic_Wars#War_between_Britain_and_France.2C_1803.E2.80.931814