The Lawrence blockhouses were blockhouses built in the spring of 1864 in Lawrence, Kansas. They were built provide defensive buildings in case of attack by Confederate guerrillas. On August 21, 1863, William C. Quantrill led a group of 400 guerrillas and Confederate Army to attack Lawrence. Lawrence had few defenses. Much of the town was destroyed. About 180 men and boys were killed. A militia became active by spring 1864 to prevent another attack.