[1] Before the American Civil War broke out, Worth was operating at a silver mine in New Mexico.

Worth was then made an Adjutant from September 5, 1861, to April 13, 1862, as well as being on the General Staff of Henry Jackson Hunt around the summer of 1862, participating at the Battle of Antietam.

Around this time, a proposal was made to make Worth the aide-de-camp to Major General Joseph Hooker but continued to serve with Hunt, going on to participate at the Battle of Gettysburg with him.

Worth was brevetted two times, once to captain on August 1, 1864, for "assault on the enemy's lines before Petersburg and in the operations in the campaign against Richmond, Va" and to major on April 9, 1865, for "gallant and meritorious service during the campaign terminating with the surrender of the insurgent army under gen RE Lee".

Around this time, Worth was transferred to serve General George Meade within the Army of the Potomac until the end of the war.