Key Facts
- Start date
- 29 May 1384
- End date
- 3 September 1384
- Duration
- ~4 months
- Cause of Castilian retreat
- Plague outbreak and Portuguese counter-attacks
- Broader conflict
- 1383–1385 Crisis
Strategic Narrative Overview
Castilian forces began the siege on 29 May 1384, surrounding Lisbon and seeking to starve the city into submission. The Portuguese defenders, led by John I of Portugal, resisted tenaciously. Outside the city, the capable commander Nuno Álvares Pereira conducted aggressive raids and constant harassing attacks against the besieging army. Meanwhile, a devastating plague outbreak swept through the Castilian ranks, inflicting severe losses and severely undermining the army's fighting strength and morale.
01 / The Origins
The siege occurred within the context of the 1383–1385 Crisis, a succession conflict in Portugal following the death of King Ferdinand I. Castile, under King John I, pressed its dynastic claim to the Portuguese throne through his wife Beatrice. To enforce this claim, John I of Castile launched a military campaign against Portugal, culminating in an attempt to take the capital, Lisbon, and subdue Portuguese resistance to Castilian rule.
03 / The Outcome
Unable to sustain the siege against both disease and Portuguese military pressure, the Castilian army was forced to withdraw on 3 September 1384, roughly four months after beginning the siege. The retreat was a catastrophic failure for Castile, and Lisbon remained in Portuguese hands. This outcome strengthened the position of John I of Portugal and set the stage for the eventual decisive Portuguese victory at the Battle of Aljubarrota in 1385.
Belligerents & Mobilization Analysis
Side A
1 belligerent
John I of Castile.
Side B
1 belligerent
John I of Portugal, Nuno Álvares Pereira.
Kinetic Engagement Axis
Scroll horizontally to view full axis. Events plotted relatively.