[1] In 1865, Brazil joined the Triple Alliance in the Paraguayan War, and Ana's sons were all called upon duty,[2] in addition to both her brothers, Manuel Jerônimo, and Joaquim Maurício.

[3] Unhappy with the fact that she would stay away from all the men in her family, she wrote a letter to Manuel Pinho de Sousa Dantas, governor of Bahia, offering to take care of injured soldiers of the Triple Alliance for the duration of the conflict.

[2][3] A wealthy woman, Ana founded a nursing house in the Paraguayan capital, then occupied and besieged by the Brazilian Army.

[3] At the end of the war, in 1870, Ana returned to Brazil and received several honors, among them the distinctions of silver and humanitarian campaign medals.

[1][2][3] Emperor Pedro II granted Ana, via decree, a lifelong pension, which she used to provide education for the four orphans that she had brought from Paraguay with her.