Medieval Portugal: Forging a Nation (1139–1415)

Portugal's medieval period is defined by its early independence from the other Iberian kingdoms and the completion of its southern expansion (Reconquista) by the mid-13th century.

1. Independence and the First Dynasty (1139–1179)

Afonso Henriques, son of Henry of Burgundy, sought independence from the Kingdom of León.

• 1139: Battle of Ourique. Afonso was proclaimed King of the Portuguese by his troops.
• 1143: Treaty of Zamora: Recognition of Portuguese independence by Alfonso VII of León.
• 1179: Papal Bull Manifestis Probatum: Pope Alexander III officially recognized Afonso I as King.

2. The Reconquista (1147–1249)

The expansion southward against the Almohad Caliphate:

• 1147: Conquest of Lisbon: Aided by English and Flemish crusaders of the Second Crusade.
• 1249: King Afonso III captured Faro, completing the conquest of the Algarve. Portugal became the first Iberian kingdom to reach its permanent continental borders.

3. Denis I: The Farmer King (1279–1325)

Denis I (Dom Dinis) transitioned Portugal from a military state to a structured kingdom.

• 1290: Foundation of the University of Coimbra.
• 1297: Treaty of Alcañices: Fixed the border between Portugal and Castile, making it the oldest stable border in Europe.
• Culture: Made Portuguese the official language of the administration.

4. The 1383–1385 Crisis

When King Ferdinand I died without a male heir, the Kingdom of Castile claimed the throne.

• Resistance: The common people and merchant class supported João, Master of Aviz.
• August 14, 1385: Battle of Aljubarrota: A vastly outnumbered Portuguese force (6,000) defeated the Castilian army (30,000) using innovative defensive tactics (ditches and archers).
• The Treaty of Windsor (1386): Established the permanent alliance with England, the world's oldest active diplomatic treaty.

5. The House of Aviz and the Shift to the Sea

The new dynasty, led by João I, looked outward. In 1415, the conquest of Ceuta marked the transition from the medieval defensive state to the age of maritime expansion. This event is traditionally cited as the end of the Portuguese Middle Ages.

Key Timeline Data

• 1139: Independence declared.
• 1147: Conquest of Lisbon.
• 1249: Conclusion of the Reconquista.
• 1290: Founding of the University of Coimbra.
• 1385: Battle of Aljubarrota (Independence secured).
• 1415: Conquest of Ceuta.