Espandor lies at the edge of Ultramar, one of the border worlds that form the outer bulwark of the primarch's realm. Less populous than the great core planets, it is a place of rugged frontier country, scattered settlements and hardy folk who dwell always in the shadow of the void's dangers. Its people are watchful by nature, for on the marches of Ultramar the enemy may come without warning.
As a frontier world, Espandor has borne the brunt of incursions that sought to breach the realm from beyond. Its lands have been ravaged by xenos raiders and worse, and each time the world has been reduced in strength, only to be rebuilt and resettled by the ceaseless labour of Ultramar's people under the guard of the Space Marines. To live on Espandor is to know that one stands upon the wall, with darkness pressing close beyond.
In the present age, with the heavens torn and the eastern reaches menaced as never before, Espandor's role as a border sentinel has grown ever more grave. Its defenders keep their vigil knowing that theirs are among the first worlds the enemy will strike, and that the safety of the realm's heartlands is bought with the blood spilled upon its frontier soil.