To annihilate the guerrillas in the Mantaro Valley, in January 1882, Lynch ordered an offensive with 5,000 men under the command of Gana and Del Canto, first towards Tarma and then southeast towards Huancayo, reaching Izcuchaca. Lynch's army suffered enormous hardships including cold temperatures, snow and mountain sickness. On July 9, 1882, they fought the emblematic Battle of La Concepción. The Chileans had to pull back with a loss of 534 soldiers: 154 in combat, 277 of disease and 103 deserters.