79th New York Infantry

"In 1858, the Scots and Scottish-Americans of the New York Caledonian Club conceived the idea of a military unit founded along Highland principles, with members drawn from their own community. They chose the numerical designation '79' to form a link with the 79th Cameron Highlanders of the British military. "

"By 27 May [1861], the 79th NYSM was mustered into federal service with the required 1,000 men, and on 4 June, they made their first camp, named Lochiel, in Washington DC. ... The regiment's first colonel was James Cameron from Pennsylvania, the brother of Simon Cameron, Lincoln's Secretary of War. Unfortunately, a minie ball abruptly ended his tenure during the first major battle of the war, First Bull Run."

"... The tradition among the members was to elect a new commander from among the officers. However, the United States government instead appointed a new colonel, a veteran of the Mexican-American War, and former governor of Washington territory, Isaac Stevens ... these factors led to a bloodless mutiny on 14 August. Federal regular troops were brought in, and the companies in mutiny relented at the point of artillery barrels. Despite this initial black mark on the honour of the regiment, the 79th quickly proved their valour in small defensive skirmishes, and were among the first regiments sent South. "

"During this period, Colonel Stevens was promoted to general, and David Morrison, a Crimean War veteran from the Black Watch, served as colonel of the 79th. Morrison reportedly refused to allow any non-Scot to be promoted above the rank of captain. The reason given for this decision was the desire to maintain Scottish leadership. The regiment seemed to be constantly struggling to maintain its Highland identity. The new recruits sent to replace fallen soldiers were of varied ethnic backgrounds, from American, Irish, English, and German communities. It is not uncommon for the British Highland regiments to have non-Scottish members, but a Scottish and especially Highland majority is always the ideal. In spite of these obstacles, the 79th succeeded in maintaining its Highland identity throughout the war. "
(from Scots in the Civil War)

They led the advance of Christ's Brigade as skirmishers, on the right of the 9th Corps line, on the afternoon of 17 September, driving along the bridge road toward Sharpsburg on the Sherrick farm.

Detail Map #7: Burnside Attacks the Lower Bridge (10 am-1 pm)
Detail Map #12: Burnside's Ninth Corps Climbs Toward Sharpsburg (3-4 pm)
Detail Map #13: AP Hill's Division Hits Burnside's Flank (4-5 pm)
Detail Map #14: Sykes' Regulars Near Sharpsburg (4-5 pm)

Tablet #56: Ninth Army Corps - 15 Sep, 7 AM to 16 Sep, 3 PM
Tablet #62: Willcox's Division, Ninth Army Corps - 16 Sep, 9 PM to 18 Sep, 6 PM
Tablet #122: Army of the Potomac - 17 Sep, 10 AM to 17 Sep, 6 PM
Tablet #99: Willcox's Division, Ninth Army Corps - 17 Sep, 2 PM to 18 Sep, 9 AM
Tablet #70, cont: Ninth Army Corps - 17 Sep, 3 PM to 17 Sep, 5 PM
Tablet #70: Ninth Army Corps - 17 Sep, 7 AM to 17 Sep, 3 PM
Tablet #57: Ninth Army Corps - 17 Sep, 7 AM to 17 Sep, 5 PM
Tablet #63: Christ's Brigade, Willcox's Division - 17 Sep, 7 AM to 18 Sep, 5 PM

See also an excellent article, Thank God Lincoln had only one 79th Highlander Regiment by Tony Mandara , posted online by the ACW Round Table (UK).from their magazine, Crossfire.