Military history of ancient Rome

The military history of ancient Rome is inseparable from its political system, based from an early date upon competition within the ruling elite. Two consuls were elected each year to head the government of the state, and in the early to mid-Republic were assigned a consular army and an area in which to campaign.
History.
From Gaius Marius and Sulla onwards, control of the army began to be tied into the political ambitions of individuals, leading to the political triumvirate of the 1st century BC and its resolution in a civil war that led to the Republic's collapse. The Empire was increasingly plagued by usurpations led or supported by military conspiracies, leading to the Crisis of the Third Century (A.D. 235–284) in the late empire and eventual final decline.
Following is a list of topics on the military history of ancient Rome.