A military veteran, he was active in the Grand Army of the Republic in the late 19th century, and he also became a property developer in Philadelphia.
Mary Custis (1808–1873), Mariah's white half-sister, was to marry the Confederate General Robert E. Lee (1807–1870).
Their eldest son, William Syphax, was eventually appointed superintendent of Washington's black segregated school district.
[5] In 1864 he entered the Union Army, serving for ten months before being honorably discharged and reaching the rank of sergeant.
[7] In the late 1800s Syphax also became involved in speculative real-estate, as Philadelphia industry was attracting many new residents.
[5] Syphax was appointed to Post 3 in the Relief Committee of the Grand Army's Department of the Potomac, which was active from February 1888 to August 1889.