[1] Born in Plymouth, Massachusetts, sometime after May 22, 1627, and before September 21, 1631 (since no birth record has been found),[2][3][4] his father and grandfather were among the colony's leaders.
Thus the younger Isaac Allerton had 3 half-siblings (all born in Leiden, Holland): Bartholomew, Remember and Mary, the last surviving passenger of the Mayflower.
Allerton and his descendants became wealthy as planters in Virginia, with indentured servants, and ultimately owned a 2,150-acre (8.7 km2) plantation on the south side of the Rappahannock River.
[22] As a major in 1667, he served under Colonel John Washington, the great-grandfather of president George Washington,[13] Settlers in the area had experienced massacres in 1622 and 1644, and when the southern Maryland Doeg sent a raiding party in 1675 that killed three colonists, the initial response was by Col. George Mason and Captain Giles Brent Jr., who destroyed their Virginia settlement (at Dogue Neck, later a plantation of the Mason family) and pursued them across the river and into the Maryland woods.
[26] Then Maryland and Virginia colonists raised a force estimated at 1000 men, the Virginians led by Cols.
Washington and Allerton and the Marylanders by Major Truman, to attack a fort the Susquehannocks had erected on an island in the Potomac River.
The colonists attacked the fort, and five Native Americans who had surrendered were slaughtered by Maryland militia, which led to charges filed against both Washington and Allerton in the General Court at Williamsburg.
[29] Allerton first served as a member of the House of Burgesses in 1667, representing Westmoreland County during a break in service of his merchant friend Nicholas Spencer.
[citation needed] Allerton served on the Governor's council from 1687 to 1691, when he, Lee and John Armistead resigned rather than take a loyalty oath to William III and Mary II, who had ousted King James.
[35][13] After a decade-plus break in service, Allerton won his last election to the House of Burgesses in 1696, but wrote that illness prevented him from attending to October 1697 session.
[38] In 1688, Allerton joined Captain George Brent of Stafford County, Virginia (who had emigrated from Maryland) and Captain Lawrence Washington as trustees of the estate of their mutual friend, Nicholas Spencer; Col. Spencer also bequeathed each man forty shillings for a mourning ring.
He was the son of James Madison, Sr., the owner of a tobacco plantation in Orange County, Virginia; and the brother of James Madison[48] (March 16, 1751 – June 28, 1836) an American politician and political philosopher who served as the fourth President of the United States (1809–1817) and is considered one of the Founding Fathers of the United States.