Afonso IV^[1][a] (Afonso Dinis; 8 February 1291 – 28 May 1357), calledthe Brave (Portuguese:o Bravo), wasKing of Portugal from 1325 until his death in 1357. He was the only legitimate son of KingDenis of Portugal andElizabeth of Aragon.

Afonso IV
Afonso IV, in Antonio de Hollanda'sGenealogy of the Royal Houses of Spain and Portugal (1530–1534)
King of Portugal
Reign	7 January 1325 – 28 May 1357
Predecessor	Denis
Successor	Peter I
Born	8 February 1291 Lisbon,Portugal
Died	28 May 1357 (aged 66) Lisbon, Portugal
Burial	Lisbon Cathedral, Portugal
Spouse	Beatrice of Castile ​ (m. 1309)​
Issue Among others...	Maria, Queen of Castile Peter I, King of Portugal Eleanor, Queen of Aragon
House	Burgundy
Father	Denis of Portugal
Mother	Elizabeth of Aragon

Afonso, born inLisbon, was the rightful heir to the Portuguese throne. However, he was not Denis' favourite son, even nearlybeginning conflict against him. Instead, the old king preferred his illegitimate son,Afonso Sanches.^[2] The notorious rivalry between the half-brothers led to civil war several times. On 7 January 1325, Afonso IV's father died and he became king, whereupon he exiled his rival, Afonso Sanches, toCastile, and stripped him of all the lands andfiefdom given by their father. From Castile, Afonso Sanches orchestrated a series of attempts to usurp the crown. After a few failed attempts at invasion, the brothers signed a peace treaty, arranged by Afonso IV's mother,Elizabeth.^[3]

In 1309, Afonso marriedBeatrice of Castile, daughter of KingSancho IV of Castile andMaría de Molina. The first-born of this union was a daughter,Maria of Portugal.

In 1325Alfonso XI of Castile entered a child-marriage withConstanza Manuel of Castile, the daughter of one of hisregents. Two years later, he had the marriage annulled so he could marry Afonso's daughter, Maria of Portugal. Maria became Queen of Castile in 1328 upon her marriage to Alfonso XI, who soon became involved publicly with a mistress.^[3] Constanza was imprisoned in a castle in Toro while her father,Don Juan Manuel, waged war against Alfonso XI until 1329. Eventually, the two reached a peaceful accord after mediation byJuan del Campo,Bishop of Oviedo; this secured Constanza's release from prison.

The public humiliation of his daughter led Afonso IV to have his son and heir,Peter I of Portugal, marry the no less aggrieved Castilianinfanta, Constanza. Afonso subsequently started a war against Castile,^[3] peace arriving four years later, through the intervention of theinfanta Maria herself. A year after the peace treaty was signed inSeville, Portuguese troops played an important role in defeating theMoors at theBattle of Río Salado in October 1340.

Political intrigue marked the last part of Afonso IV's reign, although Castille was torn by civil war after Alfonso XI died.Henry of Trastámara challenged the new KingPeter of Castile, who sent many Castilian nobles into exile in Portugal. Afonso's son Peter fell in love with his new wife'slady-in-waiting,Inês de Castro. Inês was the daughter of an important noble family fromGalicia, with links (albeit illegitimate) to both the royal houses of Castile and Portugal. Her brothers were aligned with the Trastamara faction, and became favorites of Peter, much to the dismay of others at the Portuguese court, who considered them Castilian upstarts. When Constanza died weeks after giving birth to their third child, Peter began living openly with Inês, recognized all her children as his and refused to marry anyone other than Inês herself. His father refused to go to war again against Castile, hoping the heir apparent's infatuation would end, and tried to arrange anotherdynastic marriage for him.

The situation became worse as the years passed and the aging Afonso lost control over his court. His grandson and Peter's only legitimate son,Ferdinand I of Portugal, was a sickly child, while Inês' illegitimate children thrived. Worried about his legitimate grandson's life, and the growing power of Castile within Portugal's borders, Afonso ordered Inês de Castro first imprisoned in his mother's oldconvent inCoimbra, and then murdered in 1355. He expected his son to give in and marry a princess, but Peter became enraged upon learning of his wife's decapitation in front of their young children. Peter put himself at the head of an army and devastated the country between theDouro and theMinho rivers before he was reconciled to his father in early 1357.^[4] Afonso died almost immediately after, in Lisbon in May.

Afonso IV's nicknamethe Brave alludes to his martial exploits. However, his most important accomplishments were the relative peace enjoyed by the country during his long reign and the support he gave to thePortuguese Navy. Afonso granted public funding to raise a proper commercial fleet and ordered the first Portuguese maritime explorations. The conflict with Pedro, and the explorations he initiated, eventually became the foundation of the Portuguese national epic,Os Lusíadas byLuís de Camões.

The dramatic circumstances of the relationship between father, son and Inês was used as the basis for the plot of more than twenty operas and ballets. The story with its tragicdénouement is immortalized in several plays and poems in Portuguese, such asOs Lusíadas by Luís de Camões (canto iii, stanzas 118–135), and in Spanish, includingNise lastimosa andNise laureada (1577) byJerónimo Bermúdez,Reinar despues de morir byLuis Vélez de Guevara, as well as a play by French playwrightHenry de Montherlant calledLa Reine morte (The Dead Queen).Mary Russell Mitford also wrote a drama based on the story entitledInez de Castro.Inês de Castro is a novel byMaria Pilar Queralt del Hierro in Spanish and Portuguese.

On 12 September 1309,^[5][6] Afonso marriedBeatrice of Castile, daughter ofSancho IV of Castile, andMaría de Molina,^[5][7] and had four sons and three daughters. Afonso broke the tradition of previous kings and did not have any children out of wedlock.^[b][c][d]

• Maria of Portugal, Queen of Castile (1313 – 18 January 1357),^[6][10] was the wife ofAlfonso XI of Castile,^[9] and mother of the future KingPeter of Castile. Due to the affair of her husband with his mistressEleanor de Guzmán "it was an unfortunate union from the start, contributing to dampening the relations of both kingdoms";^[11]
• Afonso (1315–1317), died in his infancy.^[6][9] Buried at the disappeared Convento das Donas of the Dominican Order inSantarém;^[12]
• Denis (born 12 February 1317), died a few months after his birth,^[6][9] and was buried inAlcobaça Monastery;^[12]
• Peter I of Portugal (8 April 1320 – 18 January 1367), the first surviving male offspring, he succeeded his father.^[6][9] When his wifeConstanza died in 1345, Beatrice took care of the education of the two orphans, theinfantesMaria andFerdinand, who later reigned as King Ferdinand I of Portugal;^[13]
• Isabel (21 December 1324^[6] – 11 July 1326), buried at theMonastery of Santa Clara-a-Velha inCoimbra;^[9][12]
• John (23 September 1326 – 21 June 1327), buried at theMonastery of São Dinis de Odivelas;^[9]
• Eleanor of Portugal, Queen of Aragon (1328–1348), born in the same year as her sister Maria's wedding,^[6] she married KingPeter IV of Aragon in November 1347 and died a year after her marriage, succumbing to theBlack Death.^[14][9]

• González Mínguez, César (2004)."Fernando IV de Castilla (1295–1312): Perfil de un reinado"(PDF).Espacio, Tiempo y Forma, Serie III, Historia Medieval (in Spanish). No. 17. Madrid: Universidad Nacional de Educación a Distancia (UNED), Facultad de Geografía e Historia. pp. 223–244.ISSN 0214-9745.
• Lourenço Menino, Vanda Lisa (2008)."Cartas de Arras da Rainha D. Beatriz (1309–1359)"(PDF).Estudios humanísticos. Historia (in Portuguese). No. 7. León: Universidad de León: Servicio de Publicaciones. pp. 349–358.ISSN 1696-0300. Archived fromthe original(PDF) on 18 April 2014. Retrieved11 June 2015.
• Rodrigues Oliveira, Ana (2010).Rainhas medievais de Portugal. Dezassete mulheres, duas dinastias, quatro séculos de História (in Portuguese). Lisbon: A esfera dos livros.ISBN 978-989-626-261-7.
• Sotto Mayor Pizarro, José Augusto (1997).Linhagens Medievais Portuguesas: Genealogias e Estratégias (1279–1325) (in Portuguese). Oporto: Doctorate thesis, author's edition.hdl:10216/18023.
• Sousa, António Caetano de (1735).Historia Genealógica da Casa Real Portugueza(PDF) (in Portuguese). Lisbon: Lisboa Occidental, of. de Joseph Antonio Da Sylva, Impressor da Academia Real.OCLC 3910285.