The Anti-Marleyan Volunteers were a group of soldiers who previously served in the Marleyan army but decided to join Zeke Yaeger in order to free the Eldians from Marleyan oppression. As detailed in the Attack on Titan anime, the members of the Volunteers were largely composed of people from different nationalities who had seen their homelands conquered by Marley. After being forced to join the Marleyan forces and fight for the country that took their homes, they grouped together under Yelena to try and take down Marley.