Maintaining a fighting force was difficult for Americans from 1776 to 1778 due to lack of funding. It was the timely intervention of the French government after the Battle of Saratoga in October 1777 that eased the burden.
It had been anticipated that the states would all contribute a "fair share" of the cost of the war to Congress, but no states did. As a result, troops often seized supplies from farmers and also seized the estates of Loyalists. Those farmers who were not loyalists received I.O.U.'s in the form of "certificates of future payment" from the Continental Congress. There was still a financial crisis as a result of which both the Congress and the states printed paper money. The paper money issued by the Congress, so called "Continental Currency," was deemed so worthless that the phrase "not worth a continental" was often heard. By the winter of 1776-77 many soldiers deserted. Others who had served the term of their enlistment also left. The army was in dire straits, and was only saved when Congress offered a bounty of $20 and one hundred acres of western lands to any soldier who fought for the duration of the war, or three years, whichever came first.
At Saratoga, Gen. Horatio Gates defeated Gen Burgoyne, and the French then believed that the Americans could win the war. As a result, a Treaty of Amity and Commerce, and a Treaty of Alliance were signed which provided needed assistance to the American army. Following this, when Spain allied with France (but not America) and the Dutch came into the European war, the British Prime Minister, Lord North, knew that Britain could not win.