The group 's first military offensive took place in 1984 with an assault on Castilla and the takeover of the village of Santander de Quilichao .
Castilla is a small town in the Cauca department .
The group 's first military offensive took place in 1984 with an assault on Castilla , a small town in the Cauca department , and the takeover of the village of Santander de Quilichao .