“MONSTROUS AND ILLEGAL PROCEEDINGS”: LAW ...

the border in Brazil. In this way, he bolstered his own personal reputation and crystallized
factional allegiances that protected cross-border relationships.
Guarch’s growing network of cross-border commercial allies in turn provided him
with an important hedge against factional reverses on his own side of the border. With
Rivera now controlling the Estado Oriental, his unitarist allies demanded support for their
own campaign against Rosas. Having fled to Buenos Aires, Oribe equally pressed the porteño
leader to support his side in the Uruguayan conflict. In 1839, Rosas’ allies in Entre Ríos
crossed into the Estado Oriental to confront Rivera. Rivera soundly defeated them, driving
the federalists back across the Uruguay River. Sensing victory, the unitarists under Lavalle
invaded the Argentine Confederation in 1840. However, their coalition began to unravel
when the French lifted their naval blockade under British pressure. With the port reopened,
Rosas sent federalist forces under Oribe’s command to confront Lavalle. After a bloody
two-year campaign, the blanco general finally defeated Lavalle’s army, driving it from the
Argentine Littoral. Rivera then decisively intervened on behalf of his old allies. He invaded
Entre Ríos with substantial support from Corrientes to the north, his Brazilian allies and the
remnants of Lavalle’s unitarists. The two Uruguayan generals met in eastern Entre Ríos at
the battle of Arroyo Grande on 6 December 1842. They did so representing cross-border
coalitions of international allies struggling to control the region. Factional conflicts had
completely blurred the Río de la Plata’s porous boundaries. 38
Oribe decimated Rivera’s forces at Arroyo Grande and then swept across the Uruguay
in early 1843. By February, Oribe had laid siege to Montevideo. Like Artigas and others
before him, however, the blanco leader lacked sufficient strength to overcome the walled-
city’s defenses. Although defeated on land, the colorados and their unitarist allies in
38 Barrán, Apogeo y Crisis, 22-23.
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