The Fourth Delaware Regiment Volunteer Infantry was organized in Wilmington from June to November 1862. The Fourth spent the winter, spring, and summer of 1863 guarding Baltimore and Washington, D.C., from quarters in Alexandria, Virginia. It joined the Army of the Potomac in May 1864 and participated in the siege of Petersburg. The Fourth continued its service with the Army of the Potomac until Lee’s surrender at Appomattox Court House. The Fourth mustered out on June 3, 1865.