Juan de Ayolas, who is Mendoza's second-in-command…
1537 CE
Mendoza promptly dispatches Ayolas to explore a possible route to Peru.
Accompanied by Domingo Martinez de Irala, Ayolas again sails upstream until he reaches a small bay on the Rio Paraguay, which he names Candelaria, the present-day Fuerte Olimpo.
Appointing Irala his lieutenant, Ayolas ventures into the Chaco and is never seen again.
After Mendoza returns unexpectedly to Spain, two other members of the expedition—Juan de Salazar de Espinosa and Gonzalo de Mendoza—explore the Rio Paraguay and meet up with Irala.
Leaving him after a short time, Salazar and Gonzalo de Mendoza descend the river, stopping at a fine anchorage.
They commence building a fort on August 15, 1537, the date of the Feast of the Assumption, and call it Asunción (Nuestra Senora Santa Maria de la Asunción).