In November 1861, Confederate troops began to build a defensive fort that would control the river approach to Clarksville, Tennessee. They mounted three guns in the fort. On February 19, 1862, Federal gunboats came up the river from Fort Donelson and reported the fort displayed a white flag and was deserted. The Federals took over the fort and enlarged it so that it would control traffic on the Hopkinsville (Kentucky) Pike. Clarksville was left with a small garrison of Union troops. In April 1862, this small garrison was made up of the 71st Ohio Volunteers commanded by Col. Rodney Mason.