As a young man, he became a U.S. government civil servant in Republican administrations, and built a network in the capital city.

[2][3] His mother was Maria Carter, an enslaved mixed-race woman who was the daughter of Ariana, a slave, and planter George Washington Parke Custis.

[3] In 1826 Custis gave Maria a bequest of 17 acres of land from the south part of the Arlington estate.

[4][a] Charles Syphax was held as a slave until freed in 1857 by his next master, Robert E. Lee, under the terms of the George W. P. Custis will.

Custis had not legally documented this transfer of land to Maria Syphax (state law may have prohibited it).

William Syphax used his connections in Washington, DC to ensure his mother regained control of her property, through a relief bill enacted by Congress in 1866.