_Denis BURGUNDY _________+
                                            | (1261 - 1324)           
                       _Afonso IV BURGUNDY _|
                      | (1290 - 1357)       |
                      |                     |_Elizabeth of BARCELONA _+
                      |                       (1271 - 1336)           
 _Peter I BURGUNDY ___|
| (1320 - 1366)       |
|                     |                      _Sancho IV IVREA ________+
|                     |                     | (1258 - 1295)           
|                     |_Beatrice of IVREA __|
|                       (1292 - 1359)       |
|                                           |_Maria of IVREA _________+
|                                             (1265 - 1321)           
|
|--John I AVIZ 
|  (1357 - 1433)
|                                            _________________________
|                                           |                         
|                      _____________________|
|                     |                     |
|                     |                     |_________________________
|                     |                                               
|_Teresa LOURENÇO ___|
                      |
                      |                      _________________________
                      |                     |                         
                      |_____________________|
                                            |
                                            |_________________________
                                                                      

[N3165] Early life

John was born in Lisbon as the natural son of King Peter I of Portugal by a woman named Teresa, who, according to the royal chronicler Fernão Lopes, was a noble Galician. In the 18th century, António Caetano de Sousa found a 16th-century document in the archives of the Torre do Tombo in which she was named as Teresa Lourenço. In 1364, by request of Nuno Freire de Andrade, a Galician Grand Master of the Order of Christ, he was created Grand Master of the Order of Aviz.

On the death without a male heir of his half-brother, King Ferdinand I, in October 1383, strenuous efforts were made to secure the succession for Beatrice, Ferdinand's only daughter. As heir presumptive, Beatrice had married king John I of Castile, but popular sentiment was against an arrangement in which Portugal would have been virtually annexed by Castile. The 1383-1385 Portuguese interregnum followed, a period of political anarchy, when no monarch ruled the country.

Acclamation

The wedding of João I of Portugal, 11 February 1387 with Philippa of Lancaster, by fifteenth century painter and manuscript illuminator Master of Wavrin, from around Lille, now in France.

On 6 April 1385, the Council of the Kingdom (the Portuguese Cortes) met in Coimbra and declared John, then Master of Aviz, to be king of Portugal.[3] This was followed by the liberation of almost all of the Minho in the course of two months as part of a war against Castile in opposition to its claims to the Portuguese throne. Soon after, the king of Castile again invaded 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 of Aviz (see Hundred Years' War). John and Nuno Álvares Pereira, his constable and talented supporter, repelled the attack in the decisive Battle of Aljubarrota on 14 August 1385.[4] John I of Castile then retreated. The Castilian forces abandoned Santarém, Torres Vedras and Torres Novas, and many other towns were delivered to John I by Portuguese nobles from the Castilian side. As a result, the stability of the Portuguese throne was permanently secured.

On 14 February 1387, John I married Philippa of Lancaster, daughter of John of Gaunt,[3] who had proved to be a worthy ally. The marriage consolidated an Anglo-Portuguese Alliance that endures to the present day.