Juneteenth is a federal holiday that commemorates the emancipation of enslaved people in the United States. The holiday originated in Galveston, Texas on June 19, 1865, when Union troops arrived to announce their freedom.
Confederate guerilla leader John Singleton Mosby and his Rangers ambushed Union troops in the winter of 1864, resulting in a bloody defeat. The story is detailed in a bestselling book about Lincoln's special forces and the shadow war during the Civil War.