After the rousing speech, it's time to cross the battlefield. You need to move across the field in between major volleys. When you look at the large group of Red Coats, you'll see the front line shooting sporadically and then the rest of the group will fire a large simultaneous volley in intervals. You don't need to worry about the front line shooting but the major volley will always hit you if you aren't in cover.
Go over the wall to the battlefield and make your way down the hill to the bit of cover directly in front of you. Behind this cover will be a couple of militiamen shooting. Get close to the cover and Connor will crouch down as if he were walking through brush. Creep up to the right side of the cover and wait for the major Red Coat volley.
Immediately after the major volley, find the low cover to the right side which has four or so militiamen behind it. Make your way to the right side of this cover and wait for the next volley. As soon as they finish their volley, round the right corner and head straight up to the small cover to the left of the large tree. When you get here, slide to the left side and wait for another volley. Directly ahead of where you are now is a large group of militiamen behind a piece of cover. After the next volley, run to this cover but don't dally because the volleys are going to come faster now.
You're almost there. Slide all the way to the left and wait for another volley. After the volley, run for the cover to the left that moves at an angle along a road. Wait for one final volley and then dash to the left along this road. The road will wrap to the right and lead to a large set of rocks that you can use to get into the trees. Use the trees to move along above the patrols. Keep moving to the north until you are right below the green marker and then climb up the cliff side.
At the top of the cliff, take cover in the nearby brush to avoid the frequent patrols. While in the bushes, move to the left and you'll find a lone tent set apart from the rest and a single enemy patrol that walks a circular route around it. Wait for him to walk past you and move to the next brush area right next to the lone tent. Wait for the guard to return and kill him.
From here, look for the row of tents to the left. Walk along these tents and you'll find some shrubs just beyond these tents that you can enter. Walk to the southern edge of these shrubs to find another lone guard walking by. Kill him from the shrubs. To your left will be a large tree and if you hug that tree and follow it to the left, you should find more brush between the tree and a tent. Hide here for a moment in case you attract attention from the large patrol circling the middle of the camp.
From this position, walk behind the tents and over to the edge of the cliff. You'll see a broken tree here. Make sure there are no guards approaching and then use this broken tree to get some elevation. Go to the end of the tree and you'll see a flag pole with the British flag there. Jump to the top of the flag pole and then from here you have a clear shot at Pitcairn. Make sure you've got him lined up and then perform an air assassination to take him out and collect your constraints.
