The Fernandine Wars: Ferdinand I’s Failed Castilian Ambitions (1369–1371)

Upon ascending the Portuguese throne in 1367, Ferdinand I of Portugal sought to expand his influence in Castile, taking advantage of the ongoing civil war between Henry II of Trastámara and the murdered Peter I of Castile.

Ferdinand’s Claim to the Castilian Throne (1369)

• In 1369, Peter I of Castile was assassinated by his half-brother, Henry of Trastámara, after a long civil war.
• As Peter’s closest legitimate male relative, Ferdinand claimed the Castilian throne, receiving support from several Castilian towns that remained loyal to Peter’s lineage.
• Henry II, now King of Castile, viewed Ferdinand’s claim as a direct threat and invaded Portugal in late 1369.

The First Fernandine War (1369–1371): A Humiliating Defeat

• The war quickly turned against Ferdinand, as Henry II’s forces—bolstered by French support—proved superior in strategy and manpower.
• Ferdinand failed to rally enough Castilian nobles to his cause and suffered several military defeats.
• The war ended in 1371 with the Treaty of Alcoutim, in which:
  • Ferdinand abandoned his claim to the Castilian throne.
  • Portugal was forced to pay Castile reparations.
  • Ferdinand agreed to marry Henry’s daughter, Leonor of Castile, to cement peace.

Political Fallout

• The treaty infuriated the Portuguese nobility, particularly when Ferdinand reneged on the arranged marriage and instead married Leonor Teles, a controversial and ambitious noblewoman.
• The failure of the war weakened Ferdinand’s credibility, yet he would continue to pursue Castilian ambitions, leading to two more Fernandine Wars (1372–1373, 1381–1382), further destabilizing Portugal.

This first disastrous war exposed Ferdinand’s military shortcomings and set Portugal on a path of continuous conflict with Castile, weakening the kingdom’s stability and paving the way for the crisis of 1383–1385, which would ultimately determine Portugal’s independence.

The term La Convivencia ("the Coexistence"), of which Toledo has long been a center, is used to describe the situation in Spanish history from about 711 to 1492—concurrent with the Reconquista ("Reconquest")—when Jews, Muslims, and Catholics in Spain live in relative peace together within the different kingdoms (during the same time, however, the Christian push to the south into Moorish land is ongoing).

The phase often refers to the interplay of cultural ideas between the three groups, and ideas of religious tolerance.

Henry II of Castile and Leon, better known as Henry of Trastámara before his coronation, is the first nobleman to employ anti-Jewish sentiment as a political tool in Spain.

This leads to an end to the convivencia, and a period of riots and pogroms, and can be seen as sowing the seeds of the persecution of the Jews by the Spanish Inquisition, which is to begin a hundred years later.

The widowed John of Gaunt, now Duke of Lancaster, had married Constance, the elder daughter and heiress of his murdered ally King Peter I of Castile, in 1371, then claimed the Castilian crown occupied by the slain monarch’s fratricidal half-brother, Henry II.

The Castilian Succession Crisis and the Turbulent Reign of Ferdinand I of Portugal (1367–1372)

When Ferdinand I of Portugal (r. 1367–1383) ascended to the throne upon his father Peter I’s death in 1367, his reign was soon entangled in dynastic conflicts with Castile, resulting in three Fernandine Wars (1369–1382) and political instability.

The Claim to the Castilian Throne (1369–1371)

• In 1369, King Peter of Castile was assassinated by his illegitimate half-brother, Henry of Trastámara, who then seized the throne as Henry II of Castile.
• As a great-grandson of Sancho IV of Castile through the female line, Ferdinand of Portugal laid claim to the Castilian throne, competing with:
  • Peter IV of Aragon
  • Charles II of Navarre
  • John of Gaunt, Duke of Lancaster, who had married Constance of Castile, the eldest daughter of Peter I of Castile, in 1370.
• Henry II, already in control of Castile, took the field to defend his claim, leading to an indecisive conflict between the rival claimants.

The Peace of Alcoutim and the Broken Marriage Pact (1371)

• In 1371, Pope Gregory XI mediated a settlement, resulting in the Peace of Alcoutim, which included:
  • Ferdinand’s renunciation of his claim to Castile.
  • The betrothal of Ferdinand to Leonor of Castile, a daughter of Henry II, to seal the peace.
• However, before the marriage could take place, Ferdinand fell in love with Leonor Telles de Menezes, the wife of one of his courtiers.
• Ferdinand had her first marriage annulled and married her instead, causing:
  • A major scandal in Portugal.
  • A revolt among the Portuguese nobility, who opposed the union.
  • Political repercussions with Castile, as the broken marriage agreement angered Henry II.

The Second Fernandine War (1372): Ferdinand’s Secret Treaty and Castilian Retaliation

• Despite his peace treaty with Castile, Ferdinand secretly allied with John of Gaunt, hoping to expel Henry II from the Castilian throne.
• In 1372, Henry II discovered this betrayal and invaded Portugal, marching on Lisbon.
• Ferdinand was forced to surrender, and the peace terms required him to:
  • Hand over several Portuguese castles to Castile.
  • Break his alliance with John of Gaunt, leaving his former ally without Portuguese support.

Aftermath and Further Conflict

• Though peace was temporarily restored, Ferdinand’s political miscalculations and diplomatic failures left Portugal increasingly vulnerable.
• His continued interference in Castilian affairs led to further wars and internal instability, culminating in the Third Fernandine War (1381–1382).
• His marriage to Leonor Telles remained deeply unpopular, and after his death in 1383, Portugal entered a succession crisis (1383–1385) that threatened its independence.

Ferdinand I’s reign was marked by reckless ambition, failed diplomacy, and military setbacks, ultimately weakening Portugal’s position and setting the stage for the rise of the House of Avis.

Ferdinand, the ninth King of Portugal and the Algarve, the second but eldest surviving son of Peter I and his wife, Constance of Castile, had succeeded his father in 1367; he is sometimes referred to as the Handsome or rarely as the Inconstant.

On the death of Peter of Castile in 1369, Ferdinand, as great grandson of Sancho IV by the female line, had laid claim to the vacant throne, for which the kings of Aragon and Navarre, and afterwards John of Gaunt, duke of Lancaster (married in 1370 to Constance, the eldest daughter of Peter), had also become competitors.

Meanwhile Henry of Trastamara, the brother (illegitimate) and conqueror of Peter, had assumed the crown and taken the field.

After one or two indecisive campaigns, all parties were ready to accept the mediation of Pope Gregory XI.

The conditions of the treaty, ratified in 1371, had included a marriage between Ferdinand and Leonora of Castile but before the union could take place the former had become passionately attached to Leonor Telles de Menezes, the wife of one of his own courtiers, and having procured a dissolution of her previous marriage, had lost no time in making her his queen.

This strange conduct, although it raised a serious insurrection in Portugal, did not at once result in a war with Henry; but the outward concord had soon been disturbed by the intrigues of the duke of Lancaster, who had prevailed on Ferdinand to enter into a secret treaty for the expulsion of Henry from his throne.

The ensuing war has been unsuccessful, despite English help; and peace is again made in 1373.