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BATTLE // September 14, 1837

Battle of Andoain

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Overview

The Battle of Andoain was a military engagement of the First Carlist War that was fought on 14 September 1837. It took place around the Basque village of Andoain, south of the main Liberal stronghold of San Sebastián. Liberal troops under Leopoldo O'Donnell had captured Andoain on 9 September, driving the Carlist garrison there to the western bank of the Oria. Over the next three days, both sides constructed breastworks amidst intermittent skirmishes. After two days of trench warfare, Carlist troops poured heavy artillery fire on the Liberal lines and launched an all-out offensive, supported by reinforcements brought in from Navarre by José Ignacio de Uranga.

Overview adapted from Wikipedia, licensed under CC BY-SA 4.0.

Significance

The Battle of Andoain, fought near the Basque village of the same name south of San Sebastián, was part of the ongoing Liberal effort to consolidate control in the Basque Country during the First Carlist War. Liberal forces under Leopoldo O'Donnell had seized Andoain on 9 September 1837, pushing the Carlist garrison across the Oria River. The subsequent Carlist counterattack, reinforced by troops from Navarre under José Ignacio de Uranga, tested Liberal forward positions in a strategically sensitive zone close to their principal stronghold at San Sebastián. Liberal casualties ranging between 100 and 750 against a numerically inferior Carlist force of roughly 3,000 suggest the counteroffensive was effective, reflecting the persistent Carlist capacity to contest Liberal advances in the northern theatre despite overall manpower disadvantages.

Tactics

Liberal forces under O'Donnell captured Andoain on 9 September, driving the Carlist to the western bank of the Oria River. Over the following days both sides constructed breastworks and engaged in intermittent skirmishing. After two days of this trench warfare, Carlist forces opened heavy artillery fire on the Liberal lines and launched a general offensive, supported by reinforcements brought in from Navarre under Uranga.

Forces & casualties

Troop strength

  • Carlists3,000
    medium
  • Liberals7,000
    medium

Liberals fielded a 2.3 : 1 numerical advantage

Casualties

  • Liberales100–750
    medium

Commanders (3)

Liberals

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Last verified June 2026
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