The Imperial Military, also known as the Imperial Armed Forces, included the various military branches of the Galactic Empire, such as the Imperial Army, the Imperial Navy, and the Stormtrooper Corps. Entities like Imperial Intelligence also supported the Imperial Military.
Following the Clone Wars and the transformation from the Galactic Republic to the Empire, the Republic Military was restructured, leading to a significant militarization effort for the newly formed Imperial Military. This force was responsible for enforcing Imperial rule, suppressing planetary rebellions, continuing the Great Jedi Purge, and pursuing remaining holdouts from the Confederacy of Independent Systems.
However, the military faced a growing rebellion, which caused concern and eventually led to the formation of the Alliance to Restore the Republic and the Galactic Civil War. Imperial stormtroopers and Star Destroyers were deployed across the galaxy to maintain control. Despite the loss of the Death Star over Yavin, the Empire nearly defeated the rebels during the Battle of Hoth. Nevertheless, the Alliance endured and persisted. Six months later, the Imperial Military suffered a major defeat at the Battle of Endor.
After repeated defeats by the New Republic and the power vacuum created by the Emperor's death after Endor, the Imperial Military ultimately fell along with the Empire. It fragmented into various remnants, awaiting the return of Grand Admiral Thrawn and a resurgence of the Imperial Military. Meanwhile, the First Order, designed from elements that fled into the Unknown Regions, constructed an entirely new military force.
Following the conclusion of the destructive three-year galaxy-wide conflict known as the Clone Wars, then Supreme Chancellor Sheev Palpatine initiated the establishment of the Galactic Empire, a dictatorship encompassing the entirety of the former Galactic Republic with himself as its head of state, the first Galactic Emperor. With significant portions of the galaxy remaining unconquered and outside Imperial control, Emperor Palpatine transformed the Grand Army of the Republic into the Imperial Military, incorporating both the Army and Navy of the previous government.
This expanded military was intended to supplement the clone troopers of the former Republic Military, as the clones had a limited service life due to their accelerated aging, and to secure Imperial dominance. Embarking on a massive militarization effort to combat remaining Separatist holdouts and bring more worlds under Imperial control, the Imperial Military became the primary instrument of Imperial enforcement and expansion from the Imperial Center. Starting Project War-Mantle early in the Imperial Era, the Empire gradually replaced clone troopers with enlisted soldiers due to lower costs and concerns that the clones' loyalty remained with the former Republic, not the New Order. Moff Wilhuff Tarkin specifically worried about the individuality the clones had developed under their Jedi officers.
In the nineteen years after the Empire's rise, a growing rebellion caused concern among the Empire's leaders, leading to the formation of the Alliance to Restore the Republic. For years, the opposing sides fought for control of sectors and systems, vying for the loyalty of their populations, with major battles on the Outer Rim worlds of Yavin 4, Hoth, and Endor. Despite defeating the Alliance on Hoth, the Battle of Yavin and Endor resulted in the destruction of both Death Stars, throwing the Empire into disarray as military leaders formed splinter fleets. The New Republic slowly pushed Imperial forces back towards the Coruscant Core.
After successive defeats by the New Republic, the scattered Imperial Military made their final stand over the Western Reaches world of Jakku. Suffering heavy losses, Grand Vizier Mas Amedda signed the Galactic Concordance, a peace treaty with the New Republic, ending the battle and the war.
The Galactic Empire was required to abandon its Imperial Academies, and the recruitment and mobilization of stormtrooper forces was prohibited. Strict disarmament treaties and significant reparations were imposed on the remnants of the Empire. Large parts of the Empire were integrated into the New Republic, and the Empire itself formally dissolved under the treaty, having already largely fragmented into remnants, with the New Republic succeeding it.
With the Empire defeated, the New Republic dismantled its military vehicles for parts. Rejecting the ideals of the Imperial Military, Chancellor Mon Mothma championed the Military Disarmament Act for the New Republic. The Empire's remnants attempted to regain power using surviving equipment, with stormtroopers and TIE fighters continuing to operate in the Outer Rim. One significant threat to the New Republic was the Shadow Council, which united disparate Imperial remnants with the promise that Grand Admiral Mitth'raw'nuruodo "Thrawn" would return and restore the Imperial Military under his leadership.
Over time, elements of the Imperial armed forces established the First Order, which remained hidden in the remote Unknown Regions as it grew stronger. Briefly influencing New Republic politics through the Centrists, the First Order eventually seceded from the Republic—a move welcomed by many—with the goal of restoring the Galactic Empire's former glory. The regime expanded its ranks with new stormtroopers by abducting and indoctrinating children under Project Resurrection. With the completion of Starkiller Base, the First Order invaded the galaxy at the start of the First Order-Resistance War, but it lacked the manpower of the former Empire. Hope for the First Order emerged with the revelation of Palpatine's survival, promising a massive military force, but Palpatine's forces were destroyed in the Battle of Exegol. The First Order then collapsed due to a galaxy-wide uprising.
The Imperial Military comprised two primary branches, the Imperial Navy and Imperial Army, along with seven smaller branches: the Imperial Department of Military Research, Diplomatic Corps, Engineering Corps, Survey and Exploration Corps, Surgical Corps, Military Police, and Imperial Intelligence. The Joint Chiefs of the Imperial Military, including the Chief of the Imperial Army and Chief of the Imperial Navy, oversaw the Army and Navy. The Stormtrooper Corps was under the Army's supervision. Supreme command belonged to the Galactic Emperor, whose authority was delegated to the acting Commander-in-Chief, his apprentice and the Emperor's Fist, Darth Vader, referred to as 1 and 2 respectively. However, the military responsibilities were not among the attributes of the Emperor's Fist and instead there existed a proper military-ranking Supreme Commander as the next-in-line martial authority. The War Ministry, led by the Minister of War, handled the military's administrative and financial needs. Imperial High Command, structured under the Joint Chiefs, was the central command division for the different military branches and included the Admiralty, General Staff, Stormtrooper Command, and Battle Station Command.
The Imperial Department of Military Research assisted the Imperial Military by improving and creating new weapons and technology. Former Republic-friendly companies, such as Sienar Fleet Systems and Kuat Drive Yards, manufactured the newer Imperial vessels. Organizations like the Naval Intelligence Agency, Imperial Intelligence, and Imperial Security Bureau often collaborated with the Imperial Military. The ISB placed internal affairs officers on all Imperial-class Star Destroyers and used informants to locate the Alliance Fleet during the Galactic Civil War.
Enlistment was available to human individuals, who trained at numerous Imperial Academy complexes across the galaxy, becoming enlisted personnel, officers, or stormtroopers. At its peak, the Empire had billions of soldiers, the largest military force in the galaxy's history. Due to the Empire's preference for humans and disdain for aliens, non-humans rarely served in the Imperial Military. Reflecting the Tarkin Doctrine, the armed forces used the threat of force to maintain control over neighboring systems. Fear and intimidation were crucial for all Imperial Military operations, exemplified by the immense size of Star Destroyers, which served as both a physical and psychological deterrent. The Empire frequently ignored the rules of war outlined in the Galactic Accord of Systems.