Ortiz de Retez Expedition to New Guinea

Background. Yñigo Ortiz de Retez was a Basque Spanish explorer who had previously served in Alvarado's 1538 expedition and was promoted to Maestre de Campo in Mindanao in 1543. Following Bernardo de la Torre's failed northern route attempt, López de Villalobos commissioned Ortiz de Retez to explore a southern route.

The Voyage. Departing Tidore on 16 May 1545 aboard the San Juan de Letrán, Ortiz de Retez navigated via the Talaud and Schoutens Islands. He coasted the northern shore of New Guinea until late August, reaching 5° S latitude before contrary winds forced a return to Tidore on 5 October 1545.

Naming and Possession. On 20 June 1545, at the mouth of the Mamberamo River, Ortiz de Retez took possession of the land for the Spanish Crown. He named the island Nueva Guinea, citing the perceived resemblance between its indigenous peoples and those of the African region of Guinea.