When did the U.S. Army officially begin?

The U.S. Army officially began on June 14, 1775, when the Continental Congress authorized the establishment of a standing army to fight against British rule during the American Revolutionary War. This date is significant as it marks the formal organization of military forces that would evolve into the modern U.S. Army.

The other dates mentioned are important in American history but do not signify the official inception of the Army. For instance, April 19, 1775, is when the battles of Lexington and Concord occurred, marking the start of armed conflict between Britain and the Colonies but not the establishment of an army. July 4, 1776, is recognized for the adoption of the Declaration of Independence, which declared the colonies' independence but again does not denote the formation of the Army. September 17, 1787, is when the U.S. Constitution was signed, establishing the framework of the U.S. government, including provisions for a military, but this is after the Army had already been founded. Thus, June 14, 1775, is the precise date when the U.S. Army was officially created.