Talk with Indian standing nearby and prepare yourself to the fight against Hollister. He is equipped with the dynamite and the effective rifle, so don't attack him in open space. I've eliminated Hollister after running in the map's centre and hiding behind the stone. When he showed up, I've played in 'cat and mouse' style , which means leaning out from the stone, shoot and hide before enemy can shoot back. After decreasing the Hollister's health level, jump down to the valley on the west and start running away, because he'll explode after a few minutes .Head to the destroyed boat's direction, but be aware - the enemy's cavalry will show up. Hide behind some stone and get rid of opponents one by one , trying to run all the time (don't be an easy target to hit). After the fight, get onto the wreck of the ship and open the safe. The next gunmen will show up and it will be Reed. Jump on the horse and start fighting . Remember to fire frequently, because Reed is regenerating fast. Take him down and the mission will end.