Benedict Arnold’s treason wasn’t a spur-of-the-moment idea. Married to an alleged loyalist, Peggy Shippen, Arnold carefully planned how he would change sides. It wasn’t enough for him to wear a different uniform. He was going to cause serious damage on his way out. The Oath of Loyalty he had signed no longer mattered to him.
From his mansion (Fairmount Park) in Philadephia, Arnold began to think Britain would win the war. He didn’t want to be on the wrong side if that happened. By the spring of 1779, he was engaged in serious, treasonous dialogue with the British.
John Andre (a former suitor of Arnold’s wife who was in charge of British secret intelligence for General Clinton) wrote a letter on May 10, 1779 to Arnold’s go-between (Joseph Stansbury). The letter spelled out the terms of Arnold’s betrayal.
It wasn’t just about being on the “right” side when the war was over. It was about money - lots of money if Arnold facilitated successful Redcoat attacks against American troops. Referring to Benedict Arnold as “Monk,” Andre observed:
...that in case any partial but important blow shou’d by his means be Struck or aimed, upon the Strength of just and pointed information & cooperation, rewards equal at least to what Such Service can be estimated at, will be given.
Some historians have recently determined there were other motives for Arnold’s actions. Perhaps he was a victim of his own disillusionment. Maybe Congress was ungrateful for his heroism and sacrifices. But Benedict Arnold’s own words leave little doubt about what was on his mind.