You agree and start giving the British fake news from Lafayette. You would tell them things like how there were whole units of troops in certain places where there were no troops at all.
You are the first to know that the British are gathering in Yorktown for a battle and tell Lafayette.
After the war you are sent back to your master. It would take a few years, but Lafayette wrote to the legislature of Virginia and requested and received your release. You are a free man in 1787.
Go back and try another story.