The Imperial Army, known formally in High Gothic as the Excertus Imperialis and the Imperialis Auxilia, respectively, (the hosts of the Imperial Army and its auxiliaries) was the ancient Imperial military force comprised of normal men and women that served as the ancestor of the Astra Militarum of the 41st Millennium. Unlike the Astra Militarum and the Navis Imperialis of the present day, the Imperial Army of the 30th and early 31st Millennia contained ground, air and space assets all within the same table of organisation and there was no differentiation between space-based and ground-based branches of the service. The origins of the Astra Militarum date back to the time of the Great Crusade in the late 30th Millennium when the Emperor of Mankind conquered a large swathe of the galaxy and forged the Imperium of Man. As the Great Crusade progressed and more worlds needed to be liberated, the Imperium’s need for more troops increased dramatically. Even the mighty transhuman armies of the Legiones Astartes could not alone complete the task at hand.