Each house had its own fleet, which patrolled within its own province, and its armies to protect its worlds. Collectively, the houses patrolled and protected the entire Expanse. Theoretically, the houses could band together and field quite an army and fleet though this hasn't happened in centuries.
The primary duties of the house navy were custom duties and apprehending criminals. They are also intended to save off actual invasions, though the Tapani sector hadn't seen an invasion in centuries by the time of the Galactic Empire.
During the reign of the Empire, most worlds were permitted small forces but the Tapani sector was trusted and factionalized enough to be given permission to maintain somewhat larger domestic forces. During this time the bulk of a house's navy were limited to intrasystem patrols, as only ten percent of a houses navy was allowed to be jump-capable. Ships in service in the house navies included Victory II-class Star Destroyers, Nebulon-B Frigates and modified Dreadnaught-class heavy cruisers. Others pooled their resources together to commission new designs from the Tallaani Shipyards.
The House FleetsEdit
Both male and female citizens of a house were admitted into a house navy, as well as aliens. Few Herglics entered naval service due to their pacific tendences and lack of navy ships built for their scale, but Mrlssi were excellent capital ship pilots and technicians.
The House GuardsEdit
The House Guards protected house assets both within a house's province and beyond. During the reign of the Empire, the House Guard regiments were the only military assets allowed to travel outside the house province.