The Inca called their empire Tahuantinsuyu (Land of the Four Quarters), which was divided into four provinces. Each province was controlled by a local governor called the apu; below him were the local rulers - the curacas, and even lower still the district headsmen - the camayoc. Through this governmental structure, the Sapa-Inca could rule the empire with impunity. Additional structures were also put in place, such as the Imperial road system, which was built along the steep inclines of mountains, interspersing bridges and stone walkways, stone steps and flat brick highways. To rule such a vast realm, the Sapa-Inca also needed constant information about the status of the far-flung reaches of the kingdom. To provide this information, the Inca formed the Chasqui Scout system. Chasquis delivered messages across the empire, relaying (by memory) important information from point to point. And in this way, a message about a peasant uprising hundreds of miles north of Cuzco could reach the king within a matter of days. Chasquis were also used by the army on campaigns to deliver messages between the moving columns. In addition, way-stations known as tambos were constructed at strategic points along the roads, giving travelers and important dignitaries a place to rest and prepare for the next leg of their journey. The Incan army was also well organized. When called upon to fight, each province would muster squadrons of men armed with maces, bows and arrows, slings, darts, and spears. During a battle, slingers would let fly a shower of rocks to soften the enemy lines. Then, archers would release their shafts, darts would fly, and then the shock troops would hit, in a torrent of screams and shouts meant to confuse and terrify the wavering opposition. Incan warfare was very successful. But nothing could prepare the empire for what was coming. After the glorious rise of Pachacuti and his son, Topa Inca, the empire began to erode under a series of internal and external disasters. A bitter civil war between half brothers Huascar and Atahuallpa stretched the empire to the breaking point. Atahuallpa won the war, quickly killed his half-brother, and declared himself king. But, in 1532 AD, Spanish Conquistadors, under the command of Francisco Pizarro, entered the Cajamarca Valley, brutally attacked Atahuallpa and his subjects, killing many and taking the Sapa-Inca hostage. Eventually, Pizarro killed Atahuallpa, pillaged the empire of its riches, and brought an end to the mighty Incan civilization.