[1] He studied at the University at Lewisburg (Pennsylvania), graduated at West Point in 1855, was assigned to duty as second lieutenant with the First Dragoons, and served in Missouri, in Kansas Territory, and with the Utah Expedition.

[2] After various western assignments he was placed in command of a military district in York County, South Carolina with orders to break up the Ku Klux Klan.

Williams suggested that he would be willing to relinquish his militia weapons and Black Union League leaders agreed to cease nighttime meetings.

The truce was broken the next day when a race riot broke out involving 500 to 700 whites in neighboring Union County killing eight blacks.

[4] Companies B, E, and K of George Armstrong Custer's Seventh U.S. Cavalry led by Merrill arrived in the area to try to quell the violence,[5] Elias Hill stepped in to lead the league, now in disarray.

As a consequence of his activities his nomination as lieutenant colonel in the regular army was held up for several years in the Senate by Southern sympathizers, but it was finally confirmed on September 27, 1890, retroactive to January 9, 1886.

[8] On February 27, 1890, Merrill was made a brevet brigadier general of the United States Army for his gallant service with the 7th Cavalry during the Battle of Canyon Creek, Montana in September 1877.

[10] In March 2016, Amazon acquired the distribution rights to Joseph Gordon-Levitt’s K Troop that is about Merrill's command in York County, South Carolina.