Historically, thermodynamics developed out of a desire to increase the efficiency of early steam engines, particularly through the work of Sadi Carnot (1824) who believed that engine efficiency was the key that could help France win the Napoleonic Wars. Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854 which stated, "Thermo-dynamics is the subject of the relation of heat to forces acting between contiguous parts of bodies, and the relation of heat to electrical agency."