Bayard was a member of the prominent Bayard family of French Huguenot ancestry who descended from Balthazar Bayard, a French Protestant, who had taken refuge in the Dutch Republic where the Huguenots found sanctuary from their religious persecution in France.
Hamilton died in Bayard"s home the next day. The first Bayards in the New World arrived in the Dutch colony of New Amsterdam with the newly appointed Governor-General Peter Stuyvesant. In the early 18th century the Bayards became among the largest landowners in the New York-New Jersey area.
Bayard was also a descendant of Stephanus Van Cortlandt and the Schuyler family.
His father, William Bayard Senior, was elected as a delegate to the 1765 Stamp Acting Congress, and was assigned to the committee that drafted language opposing taxation without representation. However, when the American Revolutionary War broke out in 1775, the father remained loyal to the crown, assisting the British troops that occupied New York City in 1776.
In 1783 Bayard married Elizabeth Cornell, a descendant of Thomas Cornell. Elizabeth was the daughter of Loyalist Samuel Cornell and Susannah Mabson.
Samuel Cornell died in 1781 in British controlled New York, having moved there from North Carolina after 1777 after refusing to take the Oath of Allegiance to the new United States.
Samuel Cornell had transferred a share of his North Carolina property to Elizabeth, however in 1779 the North Carolina Legislature voted to retroactively seize all property of Loyalists back to 1776. In November 1784 Mistress Bayard sued to have her property returned to her but was unsuccessful.
William Junior. and Elizabeth had seven children.
Catherine and Maria were each married to Duncan P. Campbell. William and Elizabeth are both buried in the Churchyard Cemetery of Trinity Church in lower Manhattan.
Although Bayard Junior. remained in New York after the war, other members of the family had fled, and many of its properties were confiscated.
