Born in 1837 in Pennsylvania, Mathew Black was the youngest child of John and Letitia Black-both natives of Ireland. As an adult, Mathew lived in either Upper or Lower St. Clair Township and was employed as a stone mason. He enlisted as a Private in Company E, 101st Pennsylvania Volunteers on September 5, 1861. He was wounded on May 31, 1862, at Fair Oaks, Virginia, and never rejoined the 101st. But on September 6, 1864, he enlisted in Battery B, 6th Pennsylvania Heavy Artillery, and his records report that during January and February 1865 he was sick in the hospital. He was mustered out June 13, 1865, at Fort Ethan Allen, Virginia.
Mathew returned to the South Hills where he lived with his wife, Rebecca (whom he married around 1850 and was listed as “keeping house” in the 1880 census), and their two daughters-Margaret, born November 10, 1859, and U. (this is the way the name appeared on the 1850 census), born about 1860. Mathew died February 28, 1885. His daughter Margaret married J.W. Richardson. She died at age 40–just five and a half years after her father.