Revolutionary War, and once again you can do a lot of videos on this but I'm just going to go over just so that you have a sense of when everything happened and when everything ended, and we can later dig deeper into the scaffold and it ends with the Treaty of Paris, and the US becomes a free, independant state and then you fast forward -- until this point the US is being governed by Congress and the Articles of Confederation, but the constitution that we have now, it was drafted in 1787, it was ratified it had to get at least 9 of the states to ratify it that happend in 1788 and then it went into effect in 1789. so it depends on what you consider the birth of the country well it would definitely the Declaration of Independence, but the country in its current form with its current institutions, with its current constitution started in 1789 and that was also the beginning of Washington's first of two terms as President and those ended in 1797.