Atanasio de la Cruz Aguirre was acting President of Uruguay

President of Uruguay

The President of the Oriental Republic of Uruguay is the head of state of Uruguay. His or her rights are determined in the Constitution of Uruguay. Conforms with the Secretariat of the Presidency, the Council of Ministers and the Director of the Office of Planning and Budget, the executive branch...

 from 1864 to 1865.

Background

Aguirre was a member of the National Party

National Party (Uruguay)

The National Party , also known as the White Party , is a major right-wing conservative political party in Uruguay, currently the major opposition party to the ruling Frente Amplio government....

; he was a Senator from 1861.

On March 1, 1864, Bernardo Berro

Bernardo Berro

Bernardo Prudencio Berro was the President of Uruguay from 1860 to 1864.-President of Uruguay :...

 stepped down from the Presidency.

President of Uruguay

He assumed the Presidency of Uruguay as next-in-line, in his capacity of President of the Senate. This lasted until February, 1865.

During the War of the Triple Alliance

War of the Triple Alliance

The Paraguayan War , also known as War of the Triple Alliance , was a military conflict in South America fought from 1864 to 1870 between Paraguay and the Triple Alliance of Argentina, Brazil, and Uruguay...

, Francisco Solano López

Francisco Solano López (politician)

Francisco Solano López Carrillo was president of Paraguay from 1862 until his death in 1870. He was officially the eldest son of president Carlos Antonio López, whom he succeeded...

 had sought to send an army to aid Aguirre against Venancio Flores

Venancio Flores

Venancio Flores Barrios was a Uruguayan political leader and general. Flores was President of Uruguay from 1854 to 1855 and from 1865 to 1868.-Background and early career:...

, who was supported by Brazilian troops.

With Montevideo

Montevideo

Montevideo is the largest city, the capital, and the chief port of Uruguay. The settlement was established in 1726 by Bruno Mauricio de Zabala, as a strategic move amidst a Spanish-Portuguese dispute over the platine region, and as a counter to the Portuguese colony at Colonia del Sacramento...

 under siege, Atanasio de la Cruz Aguirre stepped down from the Presidency in favour of Senator Tomás Villalba, who soon made peace with the Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

 Party besiegers, allied with Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

 .

This transition of power marked the coming to Presidential office of heads of state of the Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

Party, which then remained in office for nearly a century.