The Systems Alliance Army, or Alliance Army, is the primary ground force in the Alliance Military. They defend colonies, stations, and the ships surrounding colonies. They also serve as anti terrorists, recon operatives, and train militia. What defers the Alliance Army from the Marines is not only size but equipment and organization. During The First Contact War, Turian light infantry units were unprepared for the Alliance Army's Mechanized Divisions. Formations of tanks and infantry fighting vehicles cut through Turian light infantry regiments, which for the Turians, were mostly equipped to fight a similar infantry fighting force. For deployments to rough terrain, where mighty tank units would be immolbile, the Alliance Army uses its own light infantry units, "Spacebourne" divisions, and Aerospace Assault Divisions. The Alliance Army is primarily garrisoned at Earth, and at Humanity's major colonies, leaving "frontier colonies" to the more expeditionary Marines. Because Alliance Army Soldiers rarely deploy outside of Alliance Space unless during the time war, Aliens races rarely see Alliance Soldiers unless they are are Special Operations Personel, such as Major Kaiden Alenko.