| Conflict: | Battle of Guadalmesí |
| Partof: | Reconquista |
| Date: | April 8th, 1342 |
| Place: | Guadalmesí, Strait of Gibraltar |
| Result: | Castilian–Portuguese victory |
| Combatant1: | Crown of Castile Kingdom of Portugal |
| Combatant2: | Marinid Sultanate |
| Commander1: | Alfonso XI of Castile |
| Commander2: | Abu al-Hasan Ali |
| Strength1: | Unknown |
| Strength2: | Unknown |
| Casualties1: | Unknown |
| Casualties2: | Heavy |
The Battle of Guadalmesí (1342) was a naval battle between the Kingdom of Castile, with the support of the Kingdom of Portugal, against the Marinid Sultanate.
After the Battle of Getares on April 8th, 1340, where the Castilian fleet suffered a setback, the Christian forces, supported by the Kingdom of Portugal and the Republic of Genoa, rearmed and prepared for a decisive engagement. The Castilian and Portuguese fleets sought to regain control of the Strait and support the ongoing siege of Algeciras.[1]
On April 8th, 1342, the combined Castilian and Portuguese fleet confronted the Marinid forces in Guadalmesí. The Christian forces, having received reinforcements and naval support, achieved a decisive victory over the Marinid fleet.
The victory at Guadalmesí allowed Alfonso XI of Castile to proceed with the siege of Algeciras, which eventually led to the city's capture.