The Great Wall of China at Badaling

6. Southern Peak

Warning towers were built in enemy territory. These spurs were built out from the main wall and permitted the Chinese to attack the marauders from two sides. The armies were controlled from watchtowers that were built every 200 yards along the Ming walls. Locks and bolts secured the doors and windows from within creating a formidable fortress. From these towers the defenders could unleash arrows and spears from heavily protected slits. Later, cannon were used. Having discovered gunpowder, the Ming was also the first to use hand grenades and mines. Stones were also pushed through special openings to create manmade avalanches to crush the enemy. Note that they have put steps on this wall section because of the steepness.