· John I of Portugal (1358–1433), King of Portugal and the Algarve

John I KG (Portuguese: João I [ʒuˈɐ̃w̃]; Lisbon, São João da Praça (extinct), 11 April 1358 – Lisbon, Castle, 14 August 1433) was King of Portugal and the Algarve in 1385–1433. He was called the Good (sometimes the Great) or of Happy Memory, more rarely and outside Portugal, in Spain, the Bastard, and was the first to use the title Lord of Ceuta.

John was the natural son of Peter I ) Peter I (Portuguese: Pedro, pronounced [ˈpedɾu]; 19 April 1320 – 18 January 1367), by a woman named Teresa, who Fernão Lopes wrote she was a noble Galician.
In the eighteenth century, António Caetano de Sousa found a document on Torre do Tombo, of the sixteenth century, where she was named Teresa Lourenço. In 1364, by request of D. Nuno Freire de Andrade, a galician Grand Master of the Order of Christ, he was created Grand Master of the Order of Aviz, by which title he was known. He became king in 1385, after the 1383–1385 Crisis.
On the death of his half-brother Ferdinand I without a male heir in October 1383, strenuous efforts were made to secure the succession for princess Beatrice, Ferdinand's only daughter. As heiress presumptive, Beatrice had married king John I of Castile, but popular sentiment was against an arrangement in which Portugal would have become virtually annexed by Castile. The 1383–1385 Crisis followed, a period of political anarchy, when no monarch ruled the country.
On 6 April 1385, the council of the kingdom (the Portuguese Cortes) met in Coimbra and declared John, then Master of Aviz, king of Portugal. This was followed by the liberation of almost all Minho only in two months, on the war against Castile and its claims to the Portuguese throne. Soon after, the king of Castile invaded again Portugal with the purpose of conquering Lisbon and removing John I from the throne. John I of Castile was accompanied by French allied cavalry while English troops and generals took the side of John (see Hundred Years' War). John I and Nuno Álvares Pereira, his loyal Constable and talented supporter, repelled the attack on the decisive Battle of Aljubarrota (14 August 1385), where the Castilian army was virtually annihilated. John I of Castile then retreated. The Castilian forces abandoned Santarém, Torres Vedras, Torres Novas, many other towns were delivered to John I by Portuguese nobles from the Castilian side and the stability of the Portuguese throne was permanently secured.
On 11 February 1387, John I married Philippa of Lancaster, daughter of John of Gaunt, who had proved to be a worthy ally, consolidating the Anglo-Portuguese Alliance that endures to the present day.
The wedding of João I of Portugal, 11 February 1387 with Philippa of Lancaster, by XV Century painter and manuscript illuminator from around Lille, now in France, the Master of Wavrin, a.k.a. Master of Jean Wavrin
After the death of John I of Castile in 1390, without leaving issue by Beatrice, John I of Portugal ruled in peace and pursued the economic development of the country. The only significant military action was the siege and conquest of the city of Ceuta in 1415. By this step he aimed to control navigation of the African coast. But in the broader perspective, this was the first step opening the Arabian world to medieval Europe, which in fact led to the Age of Discovery with Portuguese explorers sailing across the whole world.
Contemporaneous writers describe John as a man of wit, very keen on concentrating power on himself, but at the same time with a benevolent and kind personality. His youthful education as master of a religious order made him an unusually learned king for the Middle Ages. His love for knowledge and culture was passed to his sons, often collectively referred to by Portuguese historians as the "illustrious generation" (Ínclita Geração): Edward, the future king, was a poet and a writer; Peter, the duke of Coimbra, was one of the most learned princes of his time; and Prince Henry the Navigator, the duke of Viseu, invested heavily in science and the development of nautical pursuits. In 1430, John's only surviving daughter, Isabella, married Philip the Good, Duke of Burgundy, and enjoyed an extremely refined court culture in his lands; she was the mother of Charles the Bold.