1776 On July 4th, when the colonies fought against Britain in the American War of Independence, representatives from 13 colonies unanimously adopted the Declaration of Independence. The war ended in 1783, and the United Kingdom of Great Britain recognized the independence of the United States, which was the first successful war of independence against the European colonial empire. [24] The country's Constitution was adopted on September 65438, 2007, and approved by the Parliament on June 65438, 2007. The first ten amendments, collectively known as the Bill of Rights, were approved in 179 1 to protect many basic civil rights and freedoms.