[2] Born in New Kent County to Richard Chamberlayne and his wife Mary (whose maiden name was probably Wilkinson), he inherited status and land from his paternal grandfather, a merchant who immigrated to the Virginia colony as the 18th century began.

William Chamberlayne accepted a commission as Captain of the New Kent county militia in 1793, when all white males were required to serve in such units.

In March 1814, Virginia's governor ordered Chamberlayne to Norfolk to command the units there, but officers of the U.S. Army also defending the important port city refused to serve under a militia general.

As the conflict ended, Chamberlaye resigned his commission on April 28, 1815, believing that younger men than he should be entrusted with defending the Commonwealth in the future.

[5] He gained influence in the legislature, in part due to his relative proximity to the state capitol, so during the final year of his re-elected terms, he was a member of five of the most influential standing committees, including of Claims, Courts of Justice, Privileges and Elections, Propositions and Grievances, and of Religion.

[11] In 1820, Chamberlayne owned 84 slaves in New Kent County, but only 22 members of his household were engaged in agriculture and the larger plantation in his vicinity was run by a steward for George Washington Parke Custis.

[14] Chamberlayne married Margaret Wilkinson in Henrico County, but few records of their family life survived, since New Kent County sent its official records to Richmond during the American Civil War, where they presumably burned during the conflagration started by the Confederate Army as it left the state capital in the war's final days.