Hernando Pizarro, the senior Spanish commander in…

January 1537 CE

Hernando Pizarro, the senior Spanish commander in Cuzco, encouraged by their successes, leads an attack against Manco Inca's headquarters which are now at Ollantaytambo, further away from Cuzco.

Manco Inca has gathered more than thirty thousand troops at Ollantaytambo, among them, a large number of recruits from tribes of the Amazon rainforest.

His forces are a militia army made up mostly of conscripted farmers with only rudimentary weapons training.

This is the regular fare in the Inca empire, where military service is a duty for all married men between twenty-five and fifty years old.

In combat, these soldiers are organized according to their ethnic group and led into battle by their native leaders, called kurakas.

They use melee weapons such as maces, clubs and spears as well as ranged weapons such as arrows, javelins, and slings; protective gear includes helmets, shields, and quilted cloth armor.

Against the conquistadors, wooden clubs and maces with stone or bronze heads are rarely able to penetrate Spanish armor; slings and other missile throwing weapons are somewhat more effective due to their accuracy and the large size of their projectiles.

Even so, Inca soldiers are no match for the Spanish cavalry in open terrain so they resort to fighting on rough terrain and digging pits in open fields to hinder the mobility of horses.

The attack is led by Hernando Pizarro, with a force of one hundred Spaniards (thirty infantry, seventy cavalry) and an estimated thirty thousand native allies.

One of his main assets against the Inca armies is the Spanish cavalry because horses provide a considerable advantage in hitting power, maneuverability, speed, and stamina over Inca warriors.

All Spaniards wear some kind of armor, the most commonly used types are chain mail shirts and padded cloth armor, which are lighter and cheaper than full armor suits; they are complemented by steel helmets and small iron or wooden shields.

The main Spanish offensive weapon is the steel sword, which horsemen supplement with the lance; both weapons can easily penetrate the padded armor worn by Inca troops.

Firearms, such as arquebuses are rarely used during the Spanish conquest of Peru because they are scarce, hard to use, and despised by horsemen as an ungentlemanly weapon.

Spaniards rely heavily on Indian auxiliaries because they provide thousands of warriors as well as support personnel and supplies.

These native troops have the same sorts of arms and armor as their Inca counterparts.

During the Ollantaytambo campaign, the Pizarro expedition includes thousands of auxiliaries, mainly Cañaris, Chachapoyas, and Wankas as well as several members of the Inca nobility opposed to Manco Inca.

The main access route to Ollantaytambo runs along a narrow valley formed in the mountains by the Urubamba River, which connects the site with Machu Picchu to the west and with Pisaq and Cusco to the east.

After his uprising, Manco Inca had fortified the eastern approaches to fend off attacks from the former Inca capital, now under Spanish occupation.

The first line of defense is a steep bank of terraces at Pachar, near the confluence of the Anta and Urubamba rivers.

Behind it, the Incas have channeled the Urubamba to make it cross the valley from right to left and back, thus forming two more lines backed by the fortifications of Choqana on the left bank and 'Inkapintay on the right bank.

Past them, at the plain of Mascabamba, eleven high terraces close the valley between the mountains and a deep canyon formed by the Urubamba.

The only way to continue is through the gate of T'iyupunku, a thick defensive wall with two narrow doorways.

In the event of these fortifications being overrun, the Temple Hill, a religious center surrounded by high terraces overlooking Ollantaytambo, provides a last line of defense Faced with these constraints, the Spanish expedition has to cross the river several times and fight at each ford against stiff opposition.

The bulk of the Inca army confrontsthe Spaniards from a set of terraces overlooking a plain by the Urubamba River.

Several Spanish assaults against the terraces fail against a shower of arrows, slingshots and boulders coming down from the terraces as well as from both flanks.

To hinder the efforts of the Spanish cavalry, the Incas flood the plain using previously prepared channels; water eventually reaches the horses' girths.

The defenders now counterattack some of them use Spanish weapons captured in previous encounters such as swords, bucklers, armor and even a horse, ridden by Manco Inca himself.

In a severely compromised situation, Hernando Pizarro orders a retreat; under the cover of darkness the Spanish force flees through the Urubamba valley with the Incas in pursuit and reach Cusco the next day.