After taking control of Connor, ride your horse to the place marked on the map and speak with Washington. He will give you a mission of finding the person responsible for stealing the supplies.
For that, head to the abandoned church where you will meet with your father.
Speak with him and afterwards look for traces of the thief. The first trace can be found on the road in front of the building.
The second is on the road as well, but a bit to the left.
Optional objective: Catch the cart driver within the given time - 0:30.
Examine them, head to the green zone marked on the map and start chasing the cart. For full synchronization, you will have to catch the man within 30 seconds. It's not that difficult, though you will have to remember to hold the jump button at all times during the run. As you're nearing the target, equip bare feasts and attack to knock the enemy down.
Optional objective: Do not hide in the hay cart while following the convoy.
Optional objective: Completed all the constraints in one playthrough.
As you're done interrogating the driver, head to the market spot and follow the convoy passing by there. You can do it by jumping into the hay cart, though that won't let you reach full synchronization.
To complete the optional objective, you will have to follow the thieves along the roadside. You cannot let them notice you or exit the eavesdrop circle for too long. The best way of avoiding the guards is to follow the convoy from the right side while sticking to the edge of the circle. That way you won't come across any enemy.
Optional objective: Kill camp guards without being detected - 3.
After reaching the destination, jump out of the cart into the bushes on the right and quickly kill the soldier on the left.
When he's dead, follow the two gang members while staying within the circle.
It's best to stick to the right side of the passage. From the bushes there you will be able to kill the second enemy.
The third one is waiting for you in the hut by which the pair of thieves will stop.
As you reach the end of the camp, you will note that your father has been captured by the mercenaries. Free him and kill all thirteen enemies to end the memory.