According to Emily Yellin, many of the key foot soldiers in the USO's mission were women who were "charged with providing friendly diversion for U.S. troops who were mostly men in their teens and twenties." USO centers throughout the world recruited female volunteers to serve doughnuts, dance, and just talk with the troops. USO historian Julia Carson writes that this "nostalgic hour," designed to cheer and comfort soldiers, involved "listening to music – American style" and "looking at pretty girls, like no other pretty girls in the world – American girls."