The Quadruple Alliance (April 22, 1834) – The Endgame of the Portuguese and Spanish Civil Wars

On April 22, 1834, the Quadruple Alliance was signed between Portugal, Spain, Great Britain, and France, marking the final stage of the Portuguese Civil War (1828–1834) and the broader struggle between liberalism and absolutism in the Iberian Peninsula.

The treaty aimed to permanently remove the absolutist pretenders, Dom Miguel of Portugal and Don Carlos of Spain, ensuring that constitutional monarchies prevailed in both nations.

Terms of the Quadruple Alliance

1. Exile of Dom Miguel and Don Carlos

   • Dom Miguel was banished from Portugal and forbidden from claiming the throne again.
   • Don Carlos, the Carlist claimant to the Spanish throne, was expelled from Spain, as he had opposed Isabella II’s constitutional rule.

2. Continued Spanish Troop Presence in Portugal

   • Spain committed to keeping troops in Portugal until the final defeat of Miguelite forces, ensuring stability for Queen Maria II.

3. British Naval Support

   • Britain pledged naval assistance to protect both Pedro’s constitutional forces in Portugal and Isabella II in Spain.

4. Portuguese Military Assistance Against the Carlists

   • Portugal agreed to send an auxiliary force to help Spain combat the Carlist rebellion, which had erupted over disputed succession laws.

Impact – The End of the Portuguese Civil War

• With British, Spanish, and French backing, Pedro’s forces achieved total victory, forcing Miguel’s surrender at Évora-Monte on May 26, 1834.
• Miguel formally abdicated and went into exile, marking the end of absolutist rule in Portugal.
• Queen Maria II was securely placed on the throne, and constitutional governance was restored under the Constitutional Charter of 1826.

Conclusion – The Triumph of Liberalism in Iberia

The Quadruple Alliance of 1834 played a decisive role in ensuring the success of constitutional monarchies in both Portugal and Spain. With Miguel and Don Carlos exiled, the liberal cause had prevailed, securing Portugal’s and Spain’s place in the European order as constitutional states.

However, while Portugal’s civil war ended in 1834, the First Carlist War in Spain continued until 1840, showing that the struggle between absolutism and liberalism was far from over.