Ferguson (1998) argues that given the overwhelming size advantage of the Allies in terms of population and production in 1914, the outcome of World War I was inevitable.
Some economic historians stress the importance of size. The Total War era lasted only between 19, after which point it became impossible again as nuclear weapons made devastating military force available to any small rich or large poor country. Too many people were required to labour in the fields and workshops just to feed and clothe the population, and it cost too much for government officials to count, tax, and direct them into mass combat. Before 1914, Total War was not possible because people lived much closer to subsistence. In these circumstances of ‘total war’, numbers of men and the volume of supplies played the decisive role (Chickering and Förster 2000). In WWI, multi-million man armies took the field and remained there for years, giving and taking appalling losses without disintegrating.
Leadership and psychology clearly did matter, but less so than in previous eras. The opposition between cold figures and hot blood is to some extent false. Military historians object that this leaves no room for factors such as leadership, discipline, heroism, or villainy. They emphasise things like numbers of tanks, guns, ships, airplanes and ammunition, or aggregate indices of munitions production. How much power do economic factors have in deciding the struggle for global power? To explain the outcome of WWI economic historians stress the increasingly mechanised nature of warfare, waged for years on end by massed forces.