Conflicts & Resolutions · Treaty · Peace

First Treaty of San Ildefonso

1777 · 18th century · Also known as Treaty of San Ildefonso (1777) · Part of the Spanish–Portuguese War (1776–1777)

The First Treaty of San Ildefonso was signed on 1 October 1777 by Spain and Portugal at the royal palace of La Granja de San Ildefonso, ending their war over the Río de la Plata. Portugal gave up Colonia del Sacramento and the Banda Oriental to Spain, which returned the island of Santa Catarina. The treaty also defined much of the border between their South American empires.

First Treaty of San Ildefonso
Image: Nagihuin · CC0 · Wikimedia Commons

Mentioned in 1 state history

Colonia del Sacramento

See also

Cite this entry
APA
The Epoch Institute. (2026). First Treaty of San Ildefonso. In The Epoch Institute Encyclopedia. https://the-epoch-institute.org/encyclopedia/first-treaty-of-san-ildefonso
MLA
“First Treaty of San Ildefonso.” The Epoch Institute Encyclopedia, The Epoch Institute, 2026, https://the-epoch-institute.org/encyclopedia/first-treaty-of-san-ildefonso. Accessed .
Chicago
The Epoch Institute. “First Treaty of San Ildefonso.” The Epoch Institute Encyclopedia. 2026. https://the-epoch-institute.org/encyclopedia/first-treaty-of-san-ildefonso.
Harvard
The Epoch Institute (2026) ‘First Treaty of San Ildefonso’, The Epoch Institute Encyclopedia. Available at: https://the-epoch-institute.org/encyclopedia/first-treaty-of-san-ildefonso (Accessed: ).

Last reviewed October 2026Random entry ↻