Unified Forces of the Imperium
The total of the military and paramilitary forces of the Imperium
The Unified Forces of the Imperium is a concept only. The only actual unity appears at the very top - the Imperial High Command - where the Emperor, the First Lord of the Admiralty and the Lord Marshal of the Unified Armies sit and determine the overall grand strategy for the Imperial military machines.
Even at the top, there is division and competition. Directly below the Imperial High Command come the Office of the High Imperial Marshal which is the administrative office of the Minister of Defense; The Admiralty Board which the strategic administration of the Imperial Navy and the General Staff of the Unified Armies which is the strategic administration for the Imperial Army. While certain individuals sit across all these groups, these groups are competing for the Emperor's attention and funds.
Even further down the chain of administration, the Imperial Army is mainly overseen by Subsector Dukes while the Imperial Navy is overseen by the Sector Dukes. Each service is actively competitive with the other and petty rivalries of the Nobles in command are rife. Noble Houses Vs Parvenues, Ancient rivalries, Fueds and long-standing disputes are just as prevalent within the upper levels of the Unified Forces of the Imperium as within the Imperial Palace itself.
Even the actuality of War against an external threat has failed to unite the Unified Forces of the Imperium; as can be seen by the Imperial Civil War or the clash between Regina and Mora during the Fifth Frontier War.