just after dawn on april 19, 1775, the british attempted to disarm the massachusetts militia at concord, massachusetts, thus beginning the war with the "" on july 4, 1776, founding fathers wrote the united states declaration of independence. they won the revolutionary war and started a new country. they signed the constitution in 1787 and the bill of rights in 1791. general george washington, who had led the war, became its first president. during the 19th century, the united states gained much more land in the west and began to become industrialized. in 1861, several states in the south attempted to leave the united states to start a new country called the confederate states of america. this caused the american civil war. after the war, immigration resumed. some americans became very rich in this gilded age, and the country developed one of the largest economies in the world.