Mathew Stack was born c. 1848 in Cork, Ireland, the first son of Eugene and Mary (Hennessey) Stack. He emmigrated to Kirkland, Oneida, New York, USA with his parents, and three siblings; five more siblings were bornin New York..

At the age of about 14, stating he was 18, he volunteered in Utica, NY for the Union Army--the date was July 28, 1863.

He served with the rank of "Private" with: 35th Battery Regiment, NY; Co. "A", 16th Heavy Artillery Regiment, NY; Co. "M", 1st Mounted Rifles Regiment, NY; and finally, Co. "M", 4th Provisional Cavalry, N.Y. He mustered out on November 28, 1865, in City Point, Va.

He returned home to Kirkland, NY. after the war, but left again in 1867, to join a group of gold prospectors heading to the British Columbia; he was never heard from again by his family. No wife of child ever claimed his Army pension.