After the
5 October 1910 revolution, which overthrew the Portuguese monarchy, Castilho moved to the Portuguese capital of
Lisbon, where she began to work as a teacher. She joined the
Liga das Mulheres Republicanas (Republican League of Portuguese Women), and was part of a team of nurses organised by the League in 1912. She was a member of its board, being deputy president in 1912, and treasurer in 1913 and 1914. She spoke at a rally organized to celebrate the defeat in
Chaves in October 1911 of troops loyal to the
King, who were under the leadership of
Henrique Mitchell de Paiva Couceiro. Although the life of the Republican League was fairly short, it produced a newspaper,
A Madrugada, with which Castilho was actively involved. She also worked on the publication produced by the Feminist Propaganda Association, called
A Semeadora. In 1913 she was one of the participants from Portugal in the
Seventh Conference of the International Woman Suffrage Alliance, which met in
Budapest,
Hungary. She also worked with
Obra Maternal, an institution dedicated to the protection of abandoned children, orphans and beggars, or those who were at risk of falling into the world of crime and prostitution. She was its president in 1914 and 1915. In 1913, she collaborated in a campaign in support of a decision by Parliament not to allow bail for alleged violators of minors. She attempted to found an organization called
Solidariedade Feminina, with the intention of offering daytime and evening classes for women and for girls over twelve years. However, due to the lack of a sufficient number of registrations, despite intense publicity, it ended up not being implemented. ==Freemasonry==