Wars. During Europe's major pre-revolutionary war, the Seven Years' War of 1756–1763, few armies ever numbered more than 200,000 with field forces often numbering less than 30,000. The French innovations of separate corps (allowing a single commander to efficiently command more than the traditional command span of 30,000 men) and living off the land (which allowed field armies to deploy more men without requiring an equal increase in supply arrangements such as depots and supply trains) allowed the French republic to field much larger armies than their opponents. Napoleon ensured during the time of the French republic that separate French field armies operated as a single army under his control, often allowing him to substantially outnumber his opponents. This forced his continental opponents to also increase the size of their armies, moving away from the traditional small, well-drilled Ancien Régime armies of the 18th century to mass conscript armies. The Battle of Marengo, which largely ended the War of the Second Coalition, was fought with fewer than 60,000 men on both sides. The Battle of Austerlitz which ended the War of the Third Coalition involved fewer than 160,000 men. The Battle of Friedland which led to peace with Russia in 1807 involved about 150,000 men. After these defeats, the continental powers developed various forms of mass conscription to allow them to face France on even terms, and the size of field armies increased rapidly. The battle of Wagram of 1809 involved 300,000 men, and 500,000 fought at Leipzig in 1813, of whom 150,000 were killed or wounded. About a million French soldiers became casualties (wounded, invalided or killed), a higher proportion than in the First World War. The European total may have reached 5,000,000 military deaths, including disease. France had the second-largest population in Europe by the end of the 18th century (27 million, as compared to Britain's 12 million and Russia's 35 to 40 million). It was well poised to take advantage of the levée en masse. Before Napoleon's efforts, Lazare Carnot played a large part in the reorganisation of the French army from 1793 to 1794—a time which saw previous French misfortunes reversed, with Republican armies advancing on all fronts. The French army peaked in size in the 1790s with 1.5 million Frenchmen enlisted although battlefield strength was much less. Haphazard bookkeeping, rudimentary medical support and lax recruitment standards ensured that many soldiers either never existed, fell ill