Battle of Aljubarrota (1385)

Timeline

1. 1383–1385Portugal–Castile border region · CastileAfter the death of Ferdinand I, his widow Leonor Teles married Castile's John I, alarming Portuguese nobles over Castilian annexation. Following a popular uprising in Lisbon in 1383, the Burgundian and Aviz factions split; in 1384 Castilian forces invaded and besieged Lisbon, while the Aviz faction organized resistance around John I and Nuno Álvares Pereira, building strength for the decisive battle at Aljubarrota.
2. 1385São Jorge field at Aljubarrota · Leiria DistrictJohn I led some 30,000-plus Castilian and French allied troops south, intending to establish Beatrice's right to the Portuguese throne by force. The Portuguese, numbering roughly 6,000–7,000 under John I and Nuno Álvares Pereira, met them with favorable terrain and tactical deployment. Infantry squares and flanking charges broke the enemy; the Castilian main force routed, John I was forced to retreat, and the Portuguese independence movement won a decisive military victory.
3. 1385–1386Portugal · PortugalAfter the victory at Aljubarrota, the Aviz faction had already elected John I king at the Coimbra Cortes in April 1385, and the battlefield triumph further cemented his legitimacy. In 1386 Portugal and England signed the Treaty of Windsor, forming a long-term alliance against Castile. The Batalha Monastery was later built near Aljubarrota to commemorate the battle; the Aviz dynasty was formally established and Portugal's independence long secured within the Iberian balance of power.