Margaret “Peggy” Shippen was born on July 11, 1760, to Margaret (Francis) and Edward Shippen IV. Peggy’s mother was the daughter of prominent Philadelphia lawyer Tench Francis and her father was an admiralty judge and member of Pennsylvania’s Provincial Council and Supreme Court. Peggy had three sisters and three brothers: Elizabeth, Sarah, Mary, Edward, John, and James. Her upbringing was unique for her time: she learned music, drawings, and needlework, but her true interest was politics, which she pursued under her father’s teaching. During the American Revolution, the Shippens were a well-known Loyalist family, entertaining many guests because of their status in Philadelphia society. These social events fostered connections between the family and British officers—relationships that Shippen would exploit later in the war.

After the British seizure of Philadelphia in September 1777, Shippen met Major John André, an officer under General Howe, Commander-in-Chief of the British army in the colonies. André became a regular visitor of the Shippens and took a special liking to Peggy, creating an important friendship that would facilitate her later spy work. In 1778, he invited her to a masquerade ball in tribute to the end of General Howe’s command, but her father refused to let her attend. Soon after the event, André and his troops left the city, but Peggy maintained correspondence with him. In the late summer of 1778, Shippen met Benedict Arnold, a Continental Army commander whom George Washington had recently appointed military governor of Philadelphia. Arnold proposed an engagement to Peggy’s father shortly after they began courting, but met with some resistance due to Arnold’s previous legal problems. Eventually, Edward Shippen consented to the engagement, and on April 8, 1779, 37-year-old Arnold, a widower with three children, married 19-year-old Peggy.

Peggy Shippen and Benedict Arnold had many close associations with members of the Tory party during the war years, and citizens began to view them as suspicious after hearing charges of improper expenditure leveled against the general. Shippen continued her correspondence with Major André and may have revealed valuable military secrets to the British, while her husband secretly negotiated his own dealings. Arnold was relocated to West Point in 1780 and wrote letters to Major André that exposed the military strength of the American army and their future defensive plans. Due to Shippen’s political leanings and high-level British and Loyalist contacts (used by Arnold), she may have played an integral part in Arnold’s plot. After capturing André on September 23, 1780, and receiving incriminating papers about Arnold’s betrayal, General George Washington and Alexander Hamilton, Washington’s aide-de-camp, pursued Arnold for treason. Arnold fled West Point, leaving Shippen alone with their newly-born child. Following her husband’s getaway, Shippen faked insanity to trick Washington and Hamilton into believing she was innocent, which worked and allowed Arnold to escape. Hamilton wrote of the episode:

I went in persuit [sic] of him but was much too late, and I could hardly regret the disappointment, when on my return, I saw an amiable woman frantic with distress for the loss of a husband she tenderly loved – a traitor to his country and to his fame, a disgrace to his connections. It was the most affecting scene I ever was witness to. She for a considerable time intirely [sic] lost her senses. … We have every reason to believe she was intirely [sic] unacquainted with the plan, and that her first knowlege [sic] of it was when Arnold went to tell her he must banish himself from his Country and from her forever (Hamilton to Elizabeth Schuyler).

She returned to her family in Philadelphia fearing for her safety, but was banished from the city after authorities found a letter between her and André. In November 1780, Shippen and their son joined Arnold in New York before relocating to London in 1781 after the defeat of Cornwallis in Yorktown.

After a few years in London, Arnold left for New Brunswick, Canada to embark on a business venture. In 1786, Shippen sailed to be with him. They returned to England in 1792, where they spent the rest of their lives. Shippen only briefly returned to Philadelphia in 1789 and met with unwelcoming Philadelphians during her visit, who, despite her father’s status in the city, treated her coldly and protested her presence. She and Arnold had seven children: Edward, James, Margaret (died in infancy), George (died in infancy), Sophia, George, and William. Shippen also cared for Arnold’s three children from his first marriage to Margaret Mansfield: Benedict, Richard, and Henry. On June 14, 1801, the elder Benedict Arnold died, leaving Shippen to cope with their bad reputation and many debts. Three years later, on August 24, 1804, she died from cancer, survived by four sons and a daughter. She is buried with her husband at St. Mary’s Church, Battersea, in London. Although Shippen is not commemorated in Philadelphia, she and her husband remain infamous figures of the American Revolution.