(1834 - 1893)
Home State: Pennsylvania
Command Billet: Commanding Regiment
Branch of Service: Infantry
see his Battle Report
A 29 year old teacher, he enrolled in Shippensburg on 5 October 1861 and mustered into service as Captain, Company B, 107th Pennsylvania Infantry on 20 February 1862 in Harrisburg.
On the Campaign
Colonel McCoy and Major Forney were absent sick at the start of the Maryland Campaign. Lieutenant Colonel McAllen accompanied the column but was "too feeble to keep the field" (Bates), so the command devolved on Captain MacThomson. He led them at Turner's Gap on South Mountain and at Antietam:
In the former he led in a charge with fixed bayonets which routed the enemy, Colonel Gale of the Twelfth Alabama being killed and the Lieutenant Colonel of the Fifth South Carolina wounded and taken prisoner. In the latter he led on his men up to the noted Corn-field, where he suffered severe losses, having been pitted against vastly superior numbers, but held his ground with unwavering courage.
The rest of the War
In January 1863 Major Forney died and Captain MacThompson was appointed Major, his commission dating from 17 October 1862. Soon after, Lieutenant Colonel McAllen resigned and MacThompson was appointed Lieutenant Colonel in his place on 23 February 1863.
Colonel McCoy was absent with illness after Chancellorsville and MacThomson had command on the Gettysburg Campaign. He was wounded there by "grapeshot" on 2 July 1863.
He was on court-martial duty in Philadelphia in early 1865. He was honored by brevets to Colonel and Brigadier General of Volunteers on 13 March 1865 for gallantry at Gettysburg and for war service, and was honorably mustered out 13 July 1865.
After the War
He met his wives in Washington, DC, and may have had brief Regular Army service there, but he was in St. Louis, MO by 1869.
References & notes
His service from Heitman1 and the Card File,2 both as James MacThompson. Details from a sketch in Martial Deeds,3 source of the Campaign quote above, and from family genealogists, both as James McLean Thomson. His gravesite is on Findagrave. His picture from the Massachusetts MOLLUS collection.4
He married Marie Rebecca Slye (1844-1869) in Washington, DC in September 1864 and they had a son William Henry Thomson; Marie and the boy died soon after his birth. He married again, about 1869, to Marie's 18 year old sister Jessie Genevieve Slye (1850-1923) and they had 9 children.
His name is a puzzle. He signed his official Report after Antietam as James MacThomson, and that's generally how he appears in military records - suggesting he used that name himself. I've chosen that option here. He was probably born James McLean Thomson, and it's likely that was his legal name. His father's name was Andrew Thomson and all of his children had the surname Thomson.
More on the Web
A February 1865 group photograph of General Abner Doubleday and the Philadelphia Courts-Martial Commission, including MacThomson (standing, hand in jacket), was sold by Heritage Auctions in 2009.
There is piece about him in the Spring 2014 St. Louis Genealogical Society Quarterly by Peggy Thomson Greenwood.
02/04/1834; Adams County, PA
02/20/1893; St. Louis, MO; burial in Bellefontaine Cemetery, Saint Louis, MO
1 Heitman, Francis Bernard, Historical Register and Dictionary of the United States Army 1789-1903, 2 volumes, Washington DC: US Government Printing Office, 1903, Vol. 1, pg. 682 [AotW citation 23707]
2 Commonwealth of Pennsylvania, Adjutant-General, Pennsylvania Civil War Veterans' Card File, 1861-1866, Published <2005, first accessed 01 July 2005, <http://www.digitalarchives.state.pa.us/archive.asp?view=ArchiveIndexes&ArchiveID=17> [AotW citation 23710]
3 Bates, Samuel Penniman, Martial Deeds Of Pennsylvania, Philadelphia: T. H. Davis & Co., 1876, pg. 919 [AotW citation 23711]
4 US Army, Heritage and Education Center (USAHEC), Military Order of the Loyal Legion of the United States (MOLLUS)-Massachusetts Photograph Collection, Published 2009, <https://arena.usahec.org/web/arena> [AotW citation 23709]