Coalition influence shifted with resources and endurance

John Bull traces a shift in the coalition's political and military influence from France toward Britain and then the United States. France carried the initial weight of the fighting, while its exhaustion increased the importance of British resources. He places the growth of British strategic influence roughly in late 1915 and 1916. American manpower and productive potential became increasingly important in the final phase. This is an interpretation of changing coalition influence, with the transitions described in approximate terms.