USS C. P. Williams was a mortar schooner acquired by the Union Navy during the American Civil War.

C. P. Williams was purchased by the Navy Department at New York City on September 2, 1861; fitted out as a mortar schooner; commissioned on January 21, 1862, Acting Master A. R. Langthorne in command; and reported to the Mortar Flotilla in the Mississippi River.

During the remainder of the war, she patrolled the rivers and sounds of the area, fired in the bombardments of forts, covered landing parties, and engaged detachments of Confederate cavalry ashore.

On June 9, 1865, C. P. Williams cleared Charleston, South Carolina, for Philadelphia, Pennsylvania, arriving on the 19th.

This article incorporates text from the public domain Dictionary of American Naval Fighting Ships.