Ministry of defence

Such a department usually includes all branches of the military, and is usually controlled by a defence minister or secretary of defense.

The role of a defence minister varies considerably from country to country; in some the minister is only in charge of general budget matters and procurement of equipment, while in others they are also an integral part of the operational military chain of command.

On the other hand, some countries rule that the defence minister must be civillian or was decommissioned from formal military service for a certain period of time, while some states designate the position for an active and incumbent military officer, who would usually assume one of the highest ranks amongst the respective military force such as general.

Prior to World War II, most "ministries of war" were army ministries, while the navy and the air force, if they existed as separate branches, had their own departments.

The tendency to consolidate and rename these departments, and to coordinate until then mostly separate components of defence (air, land, navy) arose after World War II.