Ida was a plain near Gladsheim on Harvest. It was destroyed during the First Battle of Harvest. After Avery Johnson and his squad left the plain, Covenant forces captured it and built a base there. Johnson's squad was then attacked once again so he ordered a retreat but lost two men by doing so.
- This is an infamous plain named after Asgard, from Norse mythology.
- This is where the first three levels of Halo Wars take place.