In 1789, Armstrong was married to Mary Stevenson (1766–1813), a daughter of large land-owner and iron manufacturer George Stevenson, Esq. (formerly the deputy surveyor-general under
Nicholas Scull for the "
territories of Pennsylvania") and sister of Dr. George Stevenson, who served with distinction at the
Battle of Brandywine. Together, they were the parents of nine children, including: • John Wilkins Armstrong (1798–1870), a doctor who married Mary Susanna Shell (1813–1855) in 1825. He was the uncle of Mrs.
William Backhouse Astor Sr. Descendants Through his son John, he was a grandfather of Mary Armstrong (1828–1898), wife of Christian Bowers Herman, and Cassius M. Armstrong (1846–1896), who married Jennie Hershman. ==References==