The so-called Ejército Grande (Big Army in English, also called the Ejército Grande Aliado Libertador, Big Allied Liberating Army) was the Argentine army that in 1852, under the command of the governor of Entre Ríos Province, Justo José de Urquiza, invaded the provinces of Santa Fe and Buenos Aires and defeated Juan Manuel de Rosas's army, which until that moment was in command of the foreign relations of the Argentine Confederation.
Made of 24,000 men, the majority from the provinces of Entre Ríos and Corrientes, also including 3,500 Brazilians, who were the only professional soldiers, and 1,500 Uruguayans. There were also some divisions commanded by porteño officers, future notable figures of the Argentine political scene, such as future presidents Bartolomé Mitre and Domingo Faustino Sarmiento. The army had 50 artillery pieces. While marching through Santa Fe, they were joined by 2,000 men from that province.
Urquiza had reclaimed from Rosas the control over the foreign relations of Entre Ríos Province at the Urquiza Announcement, of 1 May 1851. He had participated briefly in campaigns in Uruguay, forcing the end of the Uruguayan Civil War, and had formalized the alliance with Uruguay and Brazil.
In 1851 Rosas declared war on Brazil, which helped the signature of a treaty against him on 21 November 1851 by the governments of Entre Ríos, Corrientes, Uruguay and the Empire of Brazil.
To put the states of Entre Ríos and Corrientes in a situation to be able to help pay the extraordinary expenses they will have to make with the movements of their army, His majesty, the Emperor of Brazil would provide them, as a loan the monthly sum of one hundred thousand patacons for four months counting from the date in which these states ratify this agreement.