Opposing Forces

Preliminary moves

Both armies marched under the rain and set themselves up near Tarar, and subsequently marched on towards San Miguel. Santa Cruz, after stopping in Tarhuaz, then occupied the town of Yungay on 13 January.

On the night of 19 January, Santa Cruz sent Colonel Rodriguez Margariños to observe the Chilean positions. He also ordered the Bolivian Colonel Anselmo Quiroz, with 600 soldiers, to take up positions on the Pan de Azúcar Hill, while Colonel Fructuoso de la Peña advanced towards the Punyán Hill with another 200 soldiers.

At dawn on 20 January, Gen Bulnes marched with his four divisions to Yungay, whilst Santa Cruz deployed his army along the Ancash River, with Herrera's division on the right flank. The artillery was set up in the middle and, behind it, the cavalry, led by General Perez de Urdinea. Finally, Moran's division was stationed on the left flank.

Battlefield

Both forces were separated by a short valley formed by the Santa River and the mountains, with the Punyán, Ancash and Pan de Azúcar hills at the far end of this site. Behind these heights lay the deep Ancash Valley, followed by the Confederate trenches.

Confrontation on the Punyán and Pan de Azúcar hills

Bulnes decided to attack the Confederates at Punyán Hill first. Under Elespuru, Silva's Aconcagua Battalion was dispatched to clear out the hill. Silva succeeded and forced out de la Peña's, but Elespuru was mortally wounded. After them, Bulnes sent the Portales, Valdivia and Huaylas battalions.

At 9 am, a column of 400 soldiers under Jerónimo Valenzuela and formed by companies from the Carampangue, Santiago, Valparaíso and Cazadores de Perú battalions, was sent to the Pan de Azúcar Hill to assail Col. Quiroz' position. The Restorers began the slowly climbing of the hill slope under heavy fire.

The Restorer columns sustained severe losses. Valenzuela and all the officers were killed. The Carampangue's company alone was led in the end by Sergeant Candelaria Perez. The rest of the companies were severely decimated too. Nevertheless, the Restorers finally reached the summit and bayoneted the Confederates out of Pan de Azúcar Hill. All of the defenders were killed, including Quiroz himself.^[4] The Valparaíso Battalion Sergeant Jose Alegría raised the Chilean flag on the Pan de Azúcar Hill summit.^[5]

Maneuvers on the Ancash Glen

Marshall Santa Cruz sent Col. Deheza's battalion to reinforce Quiroz at Punyán Hill, marching through the Ancash Valley, but en route encountered and engaged with the Colchagua Battalion led by Col. Urriola, forcing the Chileans to respond with a bayonet charge. Bulnes ordered the Portales Battalion to aid Urriola, a maneuver that obliged the Bolivians to pull out of the valley and withdraw to Herrera's positions with the loss our a third of its initial strength.

With the Pan de Azúcar and Punyán hills conquered, Bulnes then planned a frontal attack on Santa Cruz army, which was arranged in a line of trenches on the opposite bank of the Ancash River. So, with the Chilean forces converging on the river bank, the Colchagua and Valdivia battalions were dispatched to engage the Confederate right flank, guarded by Herrera's division, while the Portales, Cazadores de Perú and the Huaylas battalions were ordered to attack Col. Moran's division. The five cannon battery of Col. Marcos Maturana set up on the Punyán heights began to shell and slowly dismantle the Confederate trenches.^[5] As the bridge over the Ancash had been destroyed, the Chileans had to go down to the river shore and march across it.

Once Bulnes' troops crossed the river, then the battle covered the entire front line, with the Restorer soldiers out in the open and the Confederates firing at them from their trenches. From this protected position, the Confederates were able to thwart the attack.^[4]

At 14:30 hrs, Gen. Pedro Bermúdez led his 3rd of Bolivia Battalion in a bayonet charge on Portales' Battalion and broke its lines. Soon after, the cavalry was sent in to cut off the Chilean retreat while the infantry advance from their protected positions to attack the Restorers troops in the open field.

Decisive blow

Witnessing the Chilean retreat, Gen. Bulnes crossed the Ancash with a battalion and reinforced Garcia, followed by the Santiago and half of Huaylas Battalion. The Chileans rallied and resumed the attack. A few Confederate battalions managed to get back to their trenches.

Perez de Urdinea's cavalry crossed the river and clashed with Baquedano's Cazadores a Caballo Cavalry Regiment. In fighting so near to the Confederate lines, Baquedano was wounded and was forced to retreat. However, the Chilean cavalry attacked again with full force, obliging Perez de Urdinea to regroup with the Confederate infantry trying to retreat to their trenches. In a massive third charge, Baquedano broke Santa Cruz's left flank and the entire Confederate front collapsed.

With both armies now engaged in the gap between the trenches and the river, the Confederates tried to resist but were surrounded and completely vanquished. The disbanded troops were pursued by the Chilean cavalry and killed. According to Gonzalo Bulnes, 277 Confederates were found dead on the road between Manco and Yungay. Santa Cruz, followed by his generals Riva Agüero, Cerdeña and Miller, left the battlefield around 15:00 hrs.