Organized at Auburn, N. Y., as the 138th Regiment New York Infantry and mustered in September 8, 1862. Left State for Washington, D. C., September 12, 1862. Designation changed to 9th Heavy Artillery December 9, 1862. 22nd New York Battery assigned to Regiment as Company "M" February 5, 1863. Company "L" organized at Albany, N. Y., and mustered in December 4, 1863. Regiment attached to 1st Brigade, Defences of Washington, D. C., north of the Potomac to December, 1862. 2nd Brigade, Defences North of the Potomac, to February, 1863. 2nd Brigade, Haskins' Division, 22nd Army Corps, Dept. of Washington, to April, 1864. 3rd Brigade, Haskins' Division, 22nd Army Corps, to May, 1864. 2nd Brigade, 3rd Division, 6th Army Corps, Army of the Potomac and Army of the Shenandoah, Middle Military Division, to June, 1865. (2nd Battalion detached with Artillery Brigade, 6th Army Corps, May 31 to July 10, 1864. 1st Brigade, Hardin's Division, 22nd Army Corps, to September 23, 1864. Keim's Provisional Brigade to October 3, 1864; then rejoined Regiment.) 1st Brigade, Hardin's Division, 22nd Army Corps, to June, 1865.

SERVICE:
Garrison duty in the Defences of Washington, D. C., till May, 1864, during which time built and garrisoned Forts Mansfield, Bayard, Gaines and Foote. Relieved from garrison duty and ordered to join Army of the Potomac in the field May 18, 1864. Rapidan Campaign May-June. North Anna River May 26. On line of the Pamunkey May 26-28. Totopotomy May 28-31. Cold Harbor June 1-12. Bethesda Church June 1-3. Before Petersburg June 18-19. Siege of Petersburg June 18-July 6 Jerusalem Plank Road, Weldon Railroad, June 22-23. Moved to Baltimore, Md., July 6-8. Battle of Monocacy, Md., July 9. Sheridan's Shenandoah Valley Campaign August 7-November 28 . Near Charlestown August 21-22. Charlestown August 29. Battle of Winchester September 19. Fisher's Hill September 22. Battle of Cedar Creek October 19. Duty at Kernstown till December. Moved to Washington, D. C., December 3; thence to Petersburg, Va. Siege of Petersburg, Va., December, 1864, to April, 1865. Fort Fisher, Petersburg, March 25, 1865. Appomattox Campaign March 28-April 9. Assault on and fall of Petersburg April 2. Amelia Springs April 5. Sailor's Creek April 6. Appomattox Court House April 9. Surrender of Lee and his army. Expedition to Danville April 17-27. Duty there and at Richmond till June. Moved to Washington, D. C. Corps Review June 8. Consolidated to four Companies June 27, 1865, and transferred to 2nd New York Heavy Artillery.
Regiment lost during service 6 Officers and 198 Enlisted men killed and mortally wounded and 3 Officers and 254 Enlisted men by disease. Total 461.