During the 1760s and early 1770s, relations between the Thirteen Colonies and Britain became increasingly strained, primarily because of resentment of the British Parliament's attempts to govern and tax American colonists without their consent. This was summarised at the time by the slogan "No taxation without representation", a perceived violation of the guaranteed Rights of Englishmen. The American Revolution began with rejection of Parliamentary authority and moves towards self-government. In response Britain sent troops to reimpose direct rule, leading to the outbreak of war in 1775. The following year, in 1776, the United States declared independence. The entry of France to the war in 1778 tipped the military balance in the Americans' favour and after a decisive defeat at Yorktown in 1781, Britain began negotiating peace terms. American independence was acknowledged at the Peace of Paris in 1783.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): When did France enter the American Revolution war?
1778