Analysis of combatants

The population of Great Britain and Ireland in 1780 was approximately 12.6 million^[141] while the population of the thirteen colonies for the same year has been estimated at 2.8 million including over 500,000 slaves.^[142] Theoretically this gave Britain a 4.5:1 manpower advantage. By comparison the Union's manpower advantage over the Confederacy in the American Civil War was only 2.5:1. In practice, the British army never had more than a slight numerical advantage over the Continental Army due to a number of factors, including the need to maintain significant numbers of troops outside of North America. Conscription outside of naval impressment did not exist in Britain at that time, and the proportion of Americans willing to serve in their own country's defense was believed to be considerably larger than the proportion of Britons willing to serve overseas. One pre-war estimate claimed that the Patriots could mobilize 100,000 men in a matter of months,^[143] but substantial loyalist or neutralist sentiment would keep Patriot forces much smaller than their potential.^[144][145]
Historians continue to debate whether the odds for American victory were long or short. John E. Ferling says the odds were so long that the American victory was "Almost A Miracle."^[146] On the other hand, Joseph Ellis says the odds favored the Americans, and asks whether there ever was any realistic chance for the British to win. He argues that this opportunity came only once, in the summer of 1776 and the British failed that test. Admiral Howe and his brother General Howe, "missed several opportunities to destroy the Continental Army....Chance, luck, and even the vagaries of the weather played crucial roles." Ellis's point is that the strategic and tactical decisions of the Howes were fatally flawed because they underestimated the challenges posed by the Patriots. Ellis concludes that once the Howe brothers failed, the opportunity for a British victory "would never come again."^[147]:11 The U.S. Army's official textbook argues that while the British difficulties were great, they were hardly insurmountable. "The British forfeited several chances for military victory in 1776–1777, and again in 1780 they might have won had they been able to throw 10,000 fresh troops into the American war."^[148]