United States of America
In 1776, thirteen British colonies declared independence. This set the American Revolutionary War into motion, which lasted seven years and grew into a full-scale international conflict. It was the first successful colonial war of independence.
One of the great things about the formation of the United States of America is its Constitution, crafted by Enlightenment-informed free-thinkers. It is the oldest written constitution still in use in the world.
Throughout the 19th century, the USA acquired territory from many sources (but not Canada). By the 1860s, a dispute between the agriculture-based southern states and the industrial north led to the American Civil War which lasted five years, ending with the north victorious, slavery abolished, and the country in one piece.