Update after researching to refresh my memory: it was actually John Andre and Joshua Hett Smith that were travelling on behalf of Benedict Arnold, and Andre accidentally revealed which side he was on to the guards because one of them, John Paulding, was wearing a Hessian coat, leading them to arrest him and find out Benedict Arnold's plot. So if he'd arrived at a different time, he almost certainly wouldn't have been caught.
I once wrote a story about time traveling terrorists who travel back in time and encourage a guy who wants to stay the night at a safe house rather than continuing on his journey, to not give in to his buddy who wants to continue the journey. Lo and behold, the United States is never born. Crazy thing is, it's a real historical event that, if changed in that way by a time traveler, likely would have resulted in no United States of America.
The guy who wanted to continue on the journey was Benedict Arnold on his way to surrender West Point to the British, which was a strategic point that would allow them to essentially cut off military support between two halves of the United States, then conquer those halves separately. But he reached a guard post where one of the guards searched him thoroughly enough to discover what his plans were. Had he arrived much later, there would have been a different guard on duty who might not have been able to catch him in his betrayal, and the U.S. would have lost the Revolution.
