We've all seen a western movie with the star, a young cavalry officer, stationed at a frontier fort made of rough, log walls. Inside this wall of logs, a raised platform (called a gallery) was used by riflemen and cannon to defend the fort from attack. If you look closely at an old fort, you'll also notice one or more heavily-built structures situated at strategic points like the corners of the walls or over the main gate These structures, called blockhouses. are often two stories high with the top floor wider than the bottom. Both levels might have window openings that were protected by heavy shutters. Cut in the shutters, as well as the upper walls were narrow slits. These slits, dating back to Medieval castles, originally protected archers. In the American West, the slits were wide enough so that a rifleman, stationed inside the wall, could pivot his weapon and aim at anything in a wide arc. From the outside, the slit offered a very small target to the attacker. The top floor of the blockhouse was the last bastion for the forts' defenders. It had a ladder that could be pulled up and a heavy trap door that could be slammed shut. Slits in the floor might be used to pour boiling water or shoot attackers who dared breach the walls. Thus, the fort and blockhouse were important buildings in North America. Once inside, a small group of armed defenders might survive attack from a far superior force.
