 By the battle's end, there were 1,018 Loyalist casualties and only 698 living prisoners, including de Peyster.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.