Red Dead Redemption II. Early in game as Arthur. Location: Lemoyne. In the NW of Bayou Nwa at the Bridge over the Kamassa River just slightly NE of Siltwater Strand. Get this Horseman 7 achievement with Arthur before you eliminate all the Lemoyne Raiders. Six raiders attack Arthur, the seventh enemy elimination can be an NPC that turns into a red dot enemy. Boom eliminate 7 enemies from horseback.