Women played a huge role in the Spanish Civil War, especially on the Republican, anti-fascist side, which I'm sure is why one of Hemingway's main characters is a woman named Pilar. While her counterpart Pablo is the leader of the guerrilla group in title, it is really Pilar who's de facto in charge and whom everyone in the group looks up to and listens to.

https://en.wikipedia.org/wiki/Women_in_the_Spanish_Civil_War