Optional objective: Stop Patriot messengers within the time limit - 3:00.
Optional objective: Do not touch the ground.
Start off by stocking up on pistol ammunition. Afterwards head to Washington's camp and speak with the Patriot leader. When you're done, ride your horse to the designated place, from where you should head onto the green path.
On your way you will pass by messengers which you have to kill. Do it with the pistol so that you don't have to get down to the ground unnecessarily.
You might also try killing them with the hidden blades, though as Connor jumps between horses there's always a chance of him missing and therefore failing the optional objective.
Optional objective: Stop the Kanien'keha with non-lethal methods.
As you reach the Indian village and meat with the shaman, you will receive yet another objective. You need to head into the woods and stop the members of your tribe.
Leave the village and the Indians will be marked with red dots on the map. Sneak to them from behind and stun with bare hands. That way you will get a full synchronization.
After eliminating the last warrior, a short cutscene will start. During it you will have to press the prompted button at the right moment and afterwards the mission will end.