Around the year 1400, the monarch Enrique III orders to build a new palacenear the Convent of Santa Clara, also put out to the river Douro.
Tordesillas is receiving importance and it obtains his major historical summitwith the Trastamaras. At the same time, in 1401, Spanish Parliament inTordesillas is celebrated summoned by Enrique III "the mourner".
In the year 1419, it is founded the Convent ofSuperior Mother of San Juanfor desire of Juan II.
In 1420 the court of the king Juan II of Castile, who was the father ofIsabel the Catholic, was in Tordesillas, in the former missing palace. Thepalace is taken by the Infant Enrique de Antequera, catching Juan Hurtado deMendoza, cost of the king and separating it from the government. He manages toenter king's rooms.All this was due tothe hatred and ambition of the Infantes de Aragon who were aspiring to managethe kingdom of Castilla in name of their cousin Juan,very young still, he was fifteen years old, though he had been already declaredmajor of age when he was fourteen.
In 1423 Don Álvaro de Luna is named condestable of Castile. Big feasts are celebratedin his honour.
In 1430, Leonor de Aragón, who was the mother of the Infantes de Aragon andmother-in-law of Juan II, is caught and imprisoned in Santa Clara.
Juan II returns to Tordesillas in 1434. His palace turned into his own jail,when the infante Don Fernando kidnaps the king, repeating a fact that DonEnrique, his brother, had already lived before. The same year, the Convent ofthe Dominicans is founded.
In 1439, the Spanish Parliament of Juan II and the Infants of Aragon getstogether, in an attempt for establishing the peace between both decrees, thatof the high nobility colligate, led by the Infantes of Aragon and the monarchicdecree led by Juan II himself and the condestable of Castile, Álvaro de Luna;this fact is known as the signature of " Tordesillas' Assurance ",under the arbitration of the count of Haro.
Duringthe reign of Juan II, not much time after being married to his second wife,Isabel of Portugal, a jealous and furious woman, she arranges the confinementof Beatriz de Silva (his first lady), in a chest for three days, an image ofthe Virgin appeared to her, who asked him to found an order in her honour,“The Order of the Purest Conception”. She was canonized in 1973 by the PopePablo VI.
In1451, Juan II and his son, the InfanteHenry, who will be Henry IV “The Impotent” met at Santa Clara to try toachieve a broken understanding upon being each one in opposite factions.
In 1453, Infant Alfonso is born in Tordesillas. His parents were Juan II and Isabel of Portugal. In future, he would be named heir of SpanishThrone by his stepbrother Enrique IV.
In 1465, Enrique IV grants privileges to Tordesillas, as the frank market. Tuesdaywas chosen as the day in which it must be celebrated, custom that is stillmaintained.
In 1467 the hospital “Mater Dei” is founded, thanks to the donation ofDoña Beatriz, daughter of D. Dionis of Portugal.
In 1468 “The Toros de Guisando Conformity” is produced, by which Isabelthe Catholic is recognized like heir to the throne by her brother, theking, pressured by the nobility that assures that Juana, the onlydaughter of Enrique IV, is the bastard daughter of Beltrán de la Cueva, right-hand man ofthe King.
In 1474 Enrique the IVth dies, then, a civil war took place between thefollowers of Juana " la Beltraneja ", supported by her husband, Alfonso V ofPortugal, and the ones who were in favour of Isabel the Catholic, who wassupported by her husband. Fernando, the Catholic, is called by the people ofTordesillas, since the warden of Castronuño, who was supporting Juana "la Beltraneja ", hadtaken possession of the village spending his time in plunder. He becomes bin Mater Dei hospital because its founder was a Portuguese woman and they tookpossession of incomes and grain. Later, Tordesillas is liberated, and taken as headquartersby the Catholic king and queen. Troops led by Fernando, the Catholic left fromhere for the battle of Bull (1476), whose victory is decisive for war course.
In 1479, it is signed Alcaçovas Agreement, (treaty of peace between Castilianand Portuguese Crowns) by which, Juana is confined in a Convent in Coimbra, and it is agreedthe marriage between the Catholic king and queen first-born girl and theInfante Alfonso of Portugal. By this Treaty, both Crowns share out the Atlantic Ocean, therefore, it would be the precedent ofthe Treatry of Tordesillas.
In 1485 the Bishop of Segovia, Juan Arias Dávila orders to opena public square according to the rank of the Village, and to build a Town Hall,giving rise to the layout of the present main square.
In 1494 one of the most important events in Tordesillas history takes place,it is the signing of the Treaty on June 7, 1494, by which the Castilian andPortuguese Crowns share out navigation rights and the conquest of AtlanticOcean.
In 1499, the Pilgrims Hospital is founded,thanks to the transfer done by D. Juan Gonzalez (the village’s archpriest) inhis will.