 Manco Inca had gathered more than 30 @,@ 000 troops at Ollantaytambo , among them , a large number of recruits from tribes of the Amazon Rainforest . Manco Inca 's forces were a militia army made up mostly of conscripted farmers with only rudimentary weapons training . This was the regular fare in the Inca empire , where military service was a duty for all married men between 25 and 50 years old . In combat , these soldiers were organized according to their ethnic group and led into battle by their native leaders , called kurakas . They used melee weapons such as maces , clubs and spears as well as ranged weapons such as arrows , javelins , and slings ; protective gear included helmets , shields , and quilted cloth armor . Against the conquistadors , wooden clubs and maces with stone or bronze heads were rarely able to penetrate Spanish armor ; slings and other missile throwing weapons were somewhat more effective due to their accuracy and the large size of their projectiles . Even so , Inca soldiers were no match for the Spanish cavalry in open terrain so they resorted to fighting on rough terrain and digging pits in open fields to hinder the mobility of horses . 
