Born in 1753 into an upper-class family of New York City, Abraham was the great-grandson and namesake of former city mayor Abraham de Peyster. Upon the outbreak of war in 1775-1776 between the rebel colonists and the colonists loyal to King George III, de Peyster chose the King's side. He served in the King's American Regiment, a regiment of Loyalists who were ordered to serve in the interior of the American colonies to re-awaken loyal sentiment and hearten those opposed to the rebels, and was commissioned in December 1776 as a captain. This became dangerous duty in the rebel colony of South Carolina, where de Peyster served under and tried to assist his regimental commander, the recklessly aggressive Patrick Ferguson. Major Ferguson had led the regiment into the Upcountry of South Carolina, where he and his men were badly outnumbered. After the hemmed-in Loyalist regiment tried to entrench themselves on a low mountaintop near Kings Pinnacle, Patriot riflemen surrounded the small detachment of King's troops on 17 October 1780. The Loyalists were besieged and, after rifle bullets struck down Major Ferguson, Captain de Peyster became the struggling regiment's scratch commander. His strategic position was hopeless and he was almost immediately forced to offer the white flag of surrender. In a scene of brutality and poor discipline, many of the Patriots continued to storm parts of the enemy encampment and shoot down their defeated enemies, and de Peyster was forced to watch many of his men get massacred. By the battle's end, there were 1,018 Loyalist casualties and only 698 living prisoners, including de Peyster.
New Brunswick
Following the decisive defeat of the British and Loyalist cause at the Battle of Yorktown in 1781, de Peyster was allowed to return to the royal garrison in his home city of New York. There, on 2 August 1783, he married Catharine Augusta Livingston. He and Catharine evacuated New York in November 1783, bound for British North America. In 1785, the couple began a new life in the recently-organized colony of New Brunswick. In consideration of his loyal services to the Crown, de Peyster was granted lands and appointed to a variety of offices. In 1792, he was appointed by royal Lieutenant Governor Thomas Carleton to be Treasurer of the new colony. While serving in office as Treasurer, however, de Peyster died in Saint John in February 1798. Although honored by his superiors and his neighbors, colonial records indicate that de Peyster died intestate and insolvent.
