Originally a bodyguard of Charles V of Spain, he was sent to Mexico to counterbalance the influence of the leader of the Spanish conquest of the Aztec Empire, Hernán Cortés, since the King worried he was becoming too powerful. As Governor of Pánuco, Guzmán cracked down hard on the supporters of Cortés, stripping him and his supporters of property and rights. He conducted numerous expeditions of conquest into the northwestern areas of Mexico, enslaving thousands of Indians and shipping them to the Caribbean colonies. In the resulting power struggles where he also made himself an enemy of important churchmen, Guzmán came out the loser.
In 1537, he was arrested for treason, abuse of power and mistreatment of the indigenous inhabitants of his territories, and he was sent to Spain in shackles. His subsequent reputation, in scholarship and popular discourse, has been that of a cruel, violent and irrational tyrant. His legacy has partly been colored by the fact that history was written largely by his political opponents such as Hernán Cortés, Juan de Zumárraga and Vasco de Quiroga.
Nuño Beltrán de Guzmán was born ca. 1485 in Guadalajara, Spain, to an old noble family. His father was Hernán Beltrán de Guzmán, a wealthy merchant and a High Constable in the Spanish Inquisition; his mother was Doña Magdalena de Guzmán. The Guzmán family supported Prince Charles in the Revolt of the Comuneros and achieved gratitude of the later Emperor. Nuño Beltrán de Guzmán received some experience in law, but never finished a degree. For a period he and his younger brother served as one of 100 royal bodyguards of Carlos V, and he accompanied the Emperor on a trip to Flanders in 1522, and undertook sensitive diplomatic missions, including one dealing with the Bishop of Cuenca (Spain).
In 1525 the Spanish crown appointed him governor of the autonomous territory of Pánuco on the Gulf Coast in what is now northeast Mexico, arriving to take up the appointment in May 1527. He traveled with Luís Ponce de Leon and arrived in Hispaniola in 1526, but here he fell sick and did not arrive in Mexico until May 1527, immediately assuming his post. Cortés had already extended his reach into Pánuco, so that Guzmán's appointment was a direct challenge. His appointment was opposed by the Pro-Cortés faction of the struggle for power in early colonial Mexico, who viewed him as an outsider with no military experience. But he had the support of the Council of Indies and the Spanish Crown who saw him as a counterbalance to the figure of Cortés whose aspirations to power worried the King of Spain. Guzmán's appointment gave heart to Spanish conquerors who had not received what they considered sufficient rewards from Cortés's distribution of encomiendas and to Spanish settlers who had not participated in the conquest but saw their paths to position and wealth blocked by the Cortés faction.
Guzmán's rule as a governor of Pánuco was stern against Spanish rivals and brutal against the Indians. He stroke down harshly against Cortés's supporters in Pánuco, accusing some of them of disloyalty to the Crown by backing Cortés's claim to the title of viceroy. Some were stripped of their property; others were tried and executed. He also incorporated territory from adjacent provinces into the province of Pánuco. These actions brought New Spain on the verge of a civil war between Guzmán and supporters of Cortés' led by Governor of New Spain Alonso de Estrada, when Estrada sent an expedition to reclaim the lands expropriated by Guzmán. During the court case against Cortés in 1529, Guzmán accused Cortés himself of being a traitor and a rebel. Bishop Juan de Zumárraga, who had traveled with Guzmán to Hispaniola, in turn accused Guzmán of being allied with the governor of Cuba, Diego Velázquez[clarification needed] and having been a sworn enemy of Cortés even before setting foot in New Spain.
As governor Guzmán instituted a system of Indian slave trade in Pánuco. During a raid along Río de Las Palmas in 1528 he allowed every horseman to take 20 Indian slaves and each footman 15. In 1529 he gave out individual slaving permissions amounting to more than 1000 slaves. Initially Guzmán did not allow Spaniards to sell slaves for export except in exchange for livestock, but later he gave more than 1500 slave licenses (each permitting the taking of between 15 and 50 slaves) in an eight-month period. The slaving operation in Pánuco expanded when Guzmán became President of the Royal Audiencia of Mexico and he had Indian slaves smuggled into Pánuco and shipped on to the Caribbean. Indian slaves were branded on the face. Taking Indian slaves was not explicitly outlawed in the period before 1528. Beginning in 1528, Indian slaving operations came under increased royal control but were not prohibited. The regulations of September 19, 1528, required slave owners to present proof of the legality of the taking of any slaves before branding. In 1529 the Crown began an investigation into the slaving enterprises of Guzmán.
In spite of his lack of success as governor, in 1529 he was appointed President of the First Audiencia, which the Council of the Indies and the Crown instated to check the ventures of industrious private individuals, such as Cortés, in New Spain.