From his letter to the King of Spain.
"In the year 1559 the marquis of Canete entrusted the expedition of the river of the Amazons to Pedro de Ursua, Navarrese, or rather, a Frenchman. He delayed the building of the boats until the year 1560 in the province of the Motilones, in Peru. The Indians are called Motilones because they wear their head shaved. These boats were made in the wet country, and upon launching most of them came to pieces. We made rafts, left the horses and supplies, and took off down the river at great risk to our persons. We then encountered the most powerful rivers of Peru, and it seemed to us to be a fresh water sea. We traveled 300 leagues from the point of launching.
This bad governor was so perverse and vicious and miserable that we could not tolerate it, and it was impossible to put up with his evil ways. Since I have a stake in the matter, excellent King and lord, I will say only that we killed him; certainly a very serious thing. We then raised a young gentleman of Seville named Don Fernando de Guzman to be our king, and we made an oath to him as such, as your royal person will see from the signatures of all those who were in this, who remain in the island of Margarita, in these Indies. They appointed me their field commander, and because I did not consent to their insults and evil deeds they tried to kill me, and I killed the new king, the captain of his guard, the lieutenant-general, his majordomo, his chaplain, a woman in league against me, a knight of Rhodes, an admiral, two ensigns, and six other of his allies. It was my intention to carry this war through and die in it, for the cruelties your ministers practice on us, and I again appointed captains and a sergeant major. They tried to kill me, and I hung them all.
We went along our route down the Maranon river while all these killings and bad events were taking place. It took us ten and a half months to reach the mouth of the river, where it enters the sea. We traveled a good hundred days, and traveled 1,500 leagues. It is a large and fearsome river, with 80 leagues of fresh water at the mouth. It is very deep, and for 800 leagues along its banks it is deserted, with no towns, as your majesty will see from the true report we have made. Along the route we took there are more than 6,000 islands. God only knows how we escaped from such a fearsome lake! I advise you, King and lord, not to attempt nor allow a fleet to be sent to this ill-fated river, because in Christian faith I swear, King and lord, that if a hundred thousand men come none will escape, because the stories are false and in this river there is nothing but despair, especially for those newly arrive from Spain...
Son of your loyal Basque vassals, and I, rebel until death against you for your ingratitude.
Lope de Aguirre, the Wanderer