Boxed In, Palace Winter, Friendly Fires (DJ set), Kindness (DJ set), Flyte, Beardyman, Nick The Record, Pierce Brothers, and Rat On The Roof have all also been added to the London fest.
As well as a full music schedule - also featuring the likes of Caribou, Lianne La Havas, and Tinariwen - Citadel will feature speeches, debates, lectures, arts, crafts, workshops, yoga, relaxation therapies, gourmet grub, and delicious drink. There's even a sports day.
Citadel will take over the capital's Victoria Park on Sunday 17 July. Tickets are on sale now.