Strategy of the Roman military

The strategy of the Roman military contains its grand strategy (the arrangements made by the state to implement its political goals through a selection of military goals, a process of diplomacy backed by threat of military action, and a dedication to the military of part of its production and resources), operational strategy (the coordination and combination of the military forces and their tactics for the goals of an overarching strategy) and, on a small scale, its military tactics (methods for military engagement in order to defeat the enemy). If a fourth rung of "engagement" is added, then the whole can be seen as a ladder, with each level from the foot upwards representing a decreasing concentration on military engagement. Whereas the purest form of tactics or engagement are those free of political imperative, the purest form of political policy does not involve military engagement. Strategy as a whole is the connection between political policy and the use of force to achieve it.

Roman Empire Trajan 117A