The Pennsylvania 3rd Heavy Artillery Regiment was organized at Philadelphia by consolidation of Robert's Battalion Pennsylvania Heavy Artillery, assigned as Companies "C," "D" and "F"; Segebarth's Battalion Marine Artillery, assigned as Companies "A," "B," "G," "H," "K" and "L," and 1st Battalion Pennsylvania Heavy ArtIllery, assigned as Company "E." Two more Companies organized at Philadelphia as Companies "I" and "M." Regiment organized February 17, 1863, and ordered to Fortress Monroe, Va. Attached to Camp Hamilton, 7th Corps, Dept. of Virginia, to May, 1863. Fortress Monroe, Va., 7th Corps, to July, 1863. Fortress Monroe, Va., Dept. of Virginia and North Carolina, to May, 1864. District of Eastern Virginia to June, 1865. Fortress Monroe, Va., Dept. of Virginia, to November, 1865. SERVICE: Duty in the Dept. of Virginia entire term, with Headquarters at Fortress Monroe, Va. Detachments of all Companies but "H" served at times in Graham's Naval Brigade and participated in several engagements on the James, Chickahominy and Nausemond Rivers. Defence of Suffolk, Va., April 12-May 4, 1863 (Cos. "A," "B," "F" and "G"). A Detachment of Company "A" in action at Smithfield, N. C., February 1, 1864, and at siege of Plymouth, N. C., April 17-20, 1864, on Gunboat "Bombshell." Companies "D," "E" and "G" in Butler's operations on south side of James River against Petersburg and Richmond May, 1864, then at various redoubts and forts on the Bermuda Hundred front till May, 1865. Company "F" was in charge of Prison Camp at Camp Hamilton, near Fortress Monroe, September, 1863, to end of war. Company "I" served at Headquarters Army of the James in Appomattox Campaign and was present at Appomattox C. H. April 9, 1865; surrender of Lee and his army. Company "M" served as Siege Artillery, Army James, in siege operations against Petersburg and Richmond May, 1864, to May, 1865. Posted principally on the Bermuda Hundred front. Detachments of Companies "F" and "G" were in attack on and capture of Fort Fisher, N..C., January 15, 1865. Company "H" served detached at Baltimore, Md., entire term; was at Gettysburg, Pa., July 2-3, 1863. Companies "A" and "B" mustered out July 11, 1865; Company "H" July 25, 1865, and Regiment November 9, 1865.