The Twenty-First Battery was mustered into the United States service April 29, 1863. May 8th following, Captain Patterson, with four guns, was sent to West Virginia, where he took an active and arduous part in military operations in that section, when he returned to Camp Dennison. May 20th, the Battery left Cincinnati, per Gunboat Exchange, as guard to Clement L. Vallandigham of Ohio, who, under sentence of a Court Martial, approved by President Lincoln, had been banished to the Rebel States It proceeded as far as Louisville in such service, when it was brought back to Camp Dennison. Here the Battery remained until John Morgan crossed the Ohio into Indiana, when it was taken to Madison, in that State, where four of its guns were placed on board steamers, to serve as patrol of the Ohio River. In this way the pursuit of Morgan was materially aided, the boats keeping close along wiht the pursuing Cavalry throughout.

September 22, 1863, the Battery started for Camp Nelson, Kentucky. Thence, October 1st, it proceeded to Greenville, Tennessee, and was kept acively at work through the roughest portions of that State until January 16, 1864. At Walker's Ford, December 2, 1863, it took prominent part in the fight, doing valuable service on the ranks of the Rebels. From that time until the close of the War, the Battery was n duty in Tennessee and Alabama, chiefly in guarding important fords and Railroad lines. July 21, 1865, it returned to Camp Taylor, near Cleveland, Ohio, where it was paid off and mustered out of service.

From History of Toledo and Lucas County, by Clark Waggoner
Volume I, page 211