For the ground forces, the player may train, customize, and command divisions consisting of various types of infantry, tanks, and other units. These divisions require equipment and manpower to fight properly. The navy and air force also require men and equipment, including the actual warships and warplanes that are used in combat. Equipment is produced by military factories, while ships are built by dockyards. These military factories and dockyards are, in turn, constructed by civilian factories, which also construct a variety of other buildings, produce consumer goods for the civilian population, and oversee commerce with other nations. Most nations are initially forced to devote a significant number of their civilian factories to producing consumer goods, but as the nation becomes increasingly mobilized, more factories will be freed up for other purposes. Mobilization is represented as a 'policy' that the player may adjust with the proper amount of political power, an abstract 'resource' that is also used to appoint new ministers and change other facets of the nation's government. In addition to mobilization, there are other policies, including the nation's stance on conscription and commerce. Land in Hearts of Iron IV is divided into tiny regions known as provinces (also called tiles), which are grouped to form states.

Hearts of iron 4 workshop