The document summarizes Paul Revere's famous midnight ride on April 18, 1775 to warn colonial militia forces that British troops were marching to Concord to seize military supplies. It describes how Revere covered 13 miles in two hours by horseback to alert leaders in key colonial towns. Upon receiving word of the British movement from signals in Boston Harbor, Revere and Joseph Warren set out to warn Samuel Adams and John Hancock in Lexington and notify militia groups along the way of the British troop movement. Within moments of Revere's arrival in Lexington, the militia assembled to resist the advancing British forces.