First Treaty of San Ildefonso
| Treaty of Peace and territorial limits between Spain and Portugal. | |
|---|---|
| Palacio La Granja, where the Treaty was signed | |
| Context | Spain and Portugal settle territorial disputes in the Río de la Plata region | 
| Signed | 1 October 1777 | 
| Location | Real Sitio de San Ildefonso | 
| Negotiators | 
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| Parties | |
The First Treaty of San Ildefonso was signed on 1 October 1777 between Spain and Portugal. It settled long-running territorial disputes between the two kingdoms' possessions in South America, primarily in the Río de la Plata region.