In early 1564, Spanish governor Pedro de Villagra was taking measures to protect all the towns and forts he already held against the growing Mapuche revolt and to organize a field army in Concepcion.

After a brief fight, 3,000 Mapuche in the Itata River valley under Loble defeated the troops of captain Francisco de Vaca coming with reinforcements from Santiago.

Meanwhile, another 3,000 warriors under Millalelmo defeated the troops coming from Angol under captain Juan Perez de Zurita, at a crossing of the Andalién River two leagues from Concepcion.

At the end of March two Spanish ships arrived bringing food that permitted the population to continue to withstand the siege for a much longer time.

On the other side the Mapuche had used up local sources of food, and without pack animals and transport vehicles were finding it difficult to bring in enough to maintain their large force.