Ironically, New York’s Irish Brigade was led by Thomas Meagher, a rebellion leader in the 1848 drive for Irish independence. Captured and sentenced to death – though commuted to life in prison – he escaped to America and organized a unit of New York Irishmen. Many Irish emigres served in the Southern armies, greatly concerned that northern victory would bring a flood of emancipated slaves northward to obtain the low-paying jobs on which they depended.
His brigade was decimated at Fredericksburg in December 1862 while advancing on Lee’s well-defended position at Marye’s Heights with 1600 men and soon retreating with barely 1000 able to walk. After further decimation at Chancellorsville and Gettysburg, Meagher’s brigade was reduced to well-under regimental strength with 600 men.
Postwar, Meagher was appointed Secretary of State for the Montana Territory by Andrew Johnson, and later as Territorial Governor. He fell off a steamboat and drowned in 1867 under mysterious circumstances, believed to be intoxication, suicide or possibly a political murder.
Irish Brigade
“At Fredericksburg the Irish Brigade was almost wiped out. When it became apparent to [its] leader that there was no prospect of being allowed to recruit new members for the New York regiments of the brigade, it was decided to consolidate the three regiments with perhaps 300 effective men into a battalion of six companies and muster out [unneeded] officers. General Meagher had previously asked leave to resign, as his brigade no longer existed except in name.
Meagher thought it a mockery to keep up a brigade with the few men left and great wrong to consolidate regiments that had attained great renown. Although its 63rd Regiment served through the Wilderness Campaign – its ranks being recruited by the addition of three new companies and by augmentations – as a distinctive Irish organization it may be regarded as nonexistent after Meagher’s resignation.”
(Foreigners in the Union Army & Navy. Ella Lonn. LSU Press, 1951. p. 122)