A Chilean army under Colonel Emilio Sotomayor had moved via Dolores rail road deep into the desert and was encamped at San Francisco Saltpeter Office, about 30 kilometers south east of the port of Pisagua.

At the beginning, Bolivian General Carlos de Villegas pressed the attack over a poorly defended battery right in the Chilean centre and almost succeeded.

Buendía hoped to defeat Sotomayor's army before the anticipated arrival of Gen. Erasmo Escala with reinforcements from Hospicio.

The allied columns became confused during the fierce fighting, and Sotomayor's men rejected the attacks over its flanks and centre.

The catastrophe for the Allies was the result of poor logistics, inefficient leadership and the unexpected desertion of the Bolivian Army under the half-hearted command of President Hilarión Daza, known as the Camarones betrayal.

On November 2, the Chileans launched an amphibious operation at Pisagua and pushed the Allies offshore, and established a beach head to transport equipment and soldiers.

Also, the loss of Pisagua deprived Gen. Buendía of the only available escape route he had left, because Iquique was under blockade since the war broke out.

With a cavalry detachment, Vergara rode on November 5 following the railroad to Dolores saltpeter office, finding the installations and water machines in good condition.

[4] Immediately, Sotomayor sent Col. Amunátegui with a regiment, two cavalry companies and one battery to Santa Catalina, about 6 kilometers south of Dolores.

[5] After his return from Tana, Lt. Col. Vergara spent great efforts in trying to convince Sotomayor to deploy the army over San Francisco Hill, instead of Santa Catalina.

and the Atacama and Coquimbo battalions, disposing Salvo’s 63 artillerymen and their eight cannons, covering south and west, according to the battle evolution, plus another six piece battery and 2 Gatling machine guns of Sgt.

[7] The Valparaíso and Navales battalions and the "Buin" 1st Line Regiment, under Urriola supported a six cannon battery directed by Capt.

The rough mountain zone over the rail road prevented any infantry incursion between San Francisco and La Encañada, so the Chilean camp over the double hill didn't fear of being attacked from its rearguard.

[7] Buendía’s plan was to break the Chilean defence at Dolores, seizing the water wells and cutting the enemy’s escape route.

He would direct the offensive over Dolores with his right wing, while Cáceres and Suárez would onset the south west face of San Francisco hill with three divisions.

On the left wing, the Bolivians under Pedro Villamil would attack the north-western edge of the hill, turning right to join at La Encañada with Buendía, who wanted to engulf the Chilean positions to take possession of Dolores.

In this plan, Buendía counted on Hilarión Daza's Bolivian troops, but the latter decided to return to Arica after a long and extenuating march.

The Chilean army had now with 6,500 men[3] and 34 cannons, thanks to Castro and Velázquez who joined in time and set between San Bartolo and Tres Clavos hills, behind the train station and the rail road in a way that could limit the access to Dolores from the plain.

Some units from Cáceres and Suárez divisions rushed to aid their companions, believing that this was the battle signal; and assaulted Salvo’s position in disarray.

Villegas began the attack with four companies in guerrilla formation under Col. Ladislao Espinar, followed by the rest of the Ayacucho, Puno, Illimani and Olañeta battalions.

When warned, Col. Juan Martínez sent two companies of his Atacama Battalion under Captain Cruz Daniel Ramírez to aid Salvo.

[12] Amunátegui managed to hold the cannons, but at high cost: 30 gunners, 82 soldiers and 7 officers were dead or wounded.

Had Villegas had taken Salvo's battery, the Allies would have turned around the cannons and destroyed the Chilean centre, breaking Sotomayor's front in half.

[9] Meanwhile, Buendía took his column to Dolores well, where he was received by heavy artillery fire from Frías', Montoya's and Carvallo's batteries.

The rest of Suárez' group, Bolognesi's and Velarde's divisions, attacked the 4th Line Regiment and the bulk of the Coquimbo Battalion, Amunátegui's right and centre.

Suárez' and Cáceres' divisions retired in order and formed a small group of soldiers from Buendía's and Villamil's columns.

The defeat was a very rough blow for the Peruvian Army Southern Command, adding the effect of Daza's withdrawal on the troops morale, specially the Bolivians.