[1] He came to Peru in 1535, under the orders of Diego de Rojas who intended to undertake the conquest of the Gran Chaco region.

In 1544, he joined the expedition of Juan Bautista Pastene that was explore the lands to the south to the Straits of Magellan in the bark San Pedro.

[1] In 1550, during the campaign to establish Concepción he led the cavalry charge that broke the leading division of the Mapuche army at the Battle of Penco.

In late 1552, Pedro de Valdivia dispatched Alderete to negotiate the confirmation of his governorship[1] with Charles V, but after he arrived back to Spain he discovered that the Emperor had transferred the suzerainty of Chile, and all his other territories, to his son Philip II, who was at the time living in England.

As Alderete was returning to America to assume his post he was taken ill with yellow fever in Panama and died there on April 7, 1556.