I unfortunately can't post a picture of the painting in question, but from what I did manage to find online, it's called George Washington Praying at Valley Forge by Paul Weber (the artist's name is super important if you look it up otherwise you're going to get the wrong painting. This one does NOT have a horse in it). In it, Washington is kneeling on one knee and some guy is hiding in the bushes watching. Who is this Peeping Tom? Anyway, someone I know asked so I figured I'd Google it for them but Google was very unhelpful in my endeavors so I'm hoping someone else here knows.
There is a lithography of that painting by P. S. Duval containing a full explanation of it: the peeping Tom is an old quaker named Potts.
The Potts family were the owners of the manor where George Washington was sheltered at Valley Forge, in case you are wondering. Do tell me, please, if that is the same painting you are talking about, as the main author listed is Lambert Sachs, although Paul Weber is also credited.
It's quite rare to see such a specific question on this sub.