The Secret Treaty of Fontainebleau (October 1807) – The Franco-Spanish Plan to Partition Portugal

As French forces under General Jean-Andoche Junot began crossing the Bidasoa River into Spain on October 12, 1807, a secret treaty between France and Spain was being finalized.

On October 27, 1807, Napoleon's Marshal of the Palace, Géraud Duroc, and Eugenio Izquierdo, an agent of Spanish Prime Minister Manuel de Godoy, signed the Treaty of Fontainebleau. This agreement outlined the partition of Portugal, aiming to divide the country into three separate entities under French and Spanish control.

The Proposed Partition of Portugal

1. The Kingdom of Northern Lusitania
   • This new kingdom, centered around Oporto (Porto) and northern Portugal, was to be ruled by Charles Louis of Etruria (the deposed King of Etruria and grandson of Charles IV of Spain).
2. The Principality of the Algarves
   • The southern portion of Portugal, including the Algarve, would be granted to Godoy, Napoleon’s Spanish ally, as a personal principality.
3. The French-Administered Lisbon Region
   • The central and most crucial part of Portugal, including Lisbon, would be placed under direct French administration, effectively making it a French colony.

Napoleon’s True Intentions – A Stepping Stone for Spanish Occupation

Despite this formal agreement, Napoleon likely had no real intention of honoring the treaty’s provisions. Instead, his true goal was to:

• Use Portugal as a pretext to introduce large French forces into Spain.
• Facilitate the subsequent takeover of Spain itself, undermining King Charles IV and his unpopular minister Godoy.
• Consolidate French dominance over the entire Iberian Peninsula, turning Spain into a puppet state.

Conclusion – The Treaty’s Role in the Peninsular War

The Treaty of Fontainebleau provided the justification for the first French invasion of Portugal in November 1807, but it also laid the groundwork for the French occupation of Spain in 1808, which would soon spark a massive Spanish uprising and lead to the Peninsular War (1808–1814).

While Portugal was the immediate target, the real victim of Napoleon’s strategy would be Spain itself, which would fall into chaos after Napoleon’s betrayal of the Spanish monarchy in 1808.