While individual states are required to provide for their own defence, the Hann Empire also has an effective central military force, which is used to bolster local defences in times of need, and provides a stick that can be used to keep the states in line with their Empire Agreements. While enforcement is, nominally, a job for the individual states, they do not want to be seen as the instigator. Instead, the Empire Council leads the way, and sends an Imperial Force, supported by units from member states. Technically, it is the States doing the enforcement, although the Empire is often the instigator and then provides the spine of any military enforcement deployment.

There are four branches of the military.

• The Imperial Guard - The most prestigious service, it provides personal and house guards for members of the Imperial Court.
• The Imperial Navy - A prestigious service, that patrols the seas and coastlines of the Empire.
• The Imperial Army - Mainly used, on a rotational basis, to support local border forces - it also provides the threat of enforcement, should this be required.
• The Civil Guard - The least prestigious of the services, The Civil Guard provide policing and basic defence for Imperial holdings, such as embassies, colonies and the like.