Military organisation is the structuring of the armed forces of a state so as to offer military capability required by the national defence policy. In some countries paramilitary forces are included in a nation’s armed forces, though not considered military. Armed forces which are not a part of military or paramilitary organisations, such as insurgent forces, often mimic military organisations, or use ad hoc structures. Military organisation is hierarchical. The use of formalised ranks in a hierarchical structure came into widespread use with the Roman Army. In modern times, executive control, management and administration of military organisations is typically undertaken by the government through a government department within the structure of public administration, often known as a Ministry of Defence, Department of Defence, or Department of War. These in turn manage Armed Services that themselves command combat, combat support and service support formations and units.