Before the first shots were fired in the American War of Independence, very few people gave the Americans (also known as the 'colonists' or 'patriots') a chance. Britain had a population of 11 million compared to the patriots 2.5 million of whom 20% were slaves. Furthermore Britain had the most powerful navy in the world, an experienced and well-armed standing army of 48,000 men and the support of tens of thousands of loyalists and Indian tribes. Britain also held the economic advantage as they could rely on the profits from the South Atlantic system and the industrial revolution. So at the beginning of the war, an American victory seemed distinctly unlikely for American forces weak and British military and naval power enormous by comparison.[i]
Foreign aid obtained by the colonists was extremely important in their victory. In 1776 France extended a secret loan to the colonies and supplied them with gunpowder. These loans of gunpowder were extremely important in enabling the patriots to defeat Britain in the Battle of Saratoga. In February 1778 France and America signed The Treaty of Alliance that stated once France entered the war against Britain, there would be no more treaties before the colonists gained liberty, sovereignty and independence.[ii] The treaty also opened both nations ports to the others commerce and guaranteed French possessions in the New World. Therefore this alliance was very important as it brought optimism and boosted the morale of the patriots. As one soldier from Pennsylvania said, "There has been a great change in this state since the news from France".
France gave money, supplies and in the last phase of the war, military force. France supplied most of the muskets, bayonets and canons used by the colonists and without French aid it is debatable if they could have won the war. For example at the Battle of Yorktown in 1781, 20 French war ships prevented Cornwallis' escape and led to the surrender of the British force and the end of the war.
Furthermore France's participation in the war and Vergennes' (French foreign minister) influence was a big factor in persuading other countries to join the American war effort. In 1779 and 1780, both Spain and Holland respectively entered against Great Britain and soon after Catherine of Russia organised the League of Armed Neutrality which when threatened by Britain in the early 1780's, responded by deterring British trade.
So foreign aid was a very important factor in America's victory as it is probable that they did not have the power to defeat the British on their own.
The logistics of the war was a second major reason for the American's victory. Britain encountered many logistical problems in the war which all contributed in some way to its defeat. Howe thought that driving the American army from the battlefield in any area would return that area to loyalty to the crown or at least neutrality. However this was not the case. Britain was only able to control areas that the military occupied so therefore when the army moved it had to abandon the area it previously occupied. As a result when a British force was defeated its only hope was to retreat to a fortified port and so if the navy was not there with its usual overwhelming power, the army would be in serious trouble, as exemplified with the Battle of Yorktown.
Another logistical problem was that the British army could not expect supplies from any area it did not occupy and also the areas Britain did occupy were too small to provision the British army.[iii] Therefore they had to be dependent on supplies from Britain but even this was often a major problem as the obtaining of these supplies was held up administratively. The British Treasury and Admiralty did not co-operate with each other to make provisioning efficient or effective. For example in 1776 Admiralty agents insisted that army suppliers be licensed and applications accompanied...