The Outer Rim Sieges marked the concluding military operations of the Clone Wars, a conflict between the Galactic Republic and the Confederacy of Independent Systems. These sieges unfolded in 19 BBY, which was the third and final year of the war. This campaign took place as the Confederacy was forced back towards the spiral arms of the galaxy. While the Republic maintained pressure on the Separatists in these regions, the sieges also coincided with a counteroffensive launched by General Grievous, the Supreme Commander of the Separatist Droid Army, which nearly overwhelmed the Republic Military. In response to this assault, Jedi Generals were dispatched to aid the Grand Army of the Republic. Despite an initial standoff during a time, the sieges ultimately shifted the war's momentum in favor of the Republic, instilling fear within the Confederacy about the potential loss of the Clone Wars.
The final campaign of the Clone Wars, a large-scale conflict between the Galactic Republic and the Confederacy of Independent Systems that had engulfed the galaxy since 22 BBY, were the Outer Rim Sieges, which were fought in 19 BBY. The Outer Rim Territories had long been a primary battleground between the Confederacy and Republic. Throughout the war, the Republic struggled to contain the Separatist advances in the Outer Rim. Confederate forces, led by General Grievous, achieved several victories against the Republic early in the war, including the Malevolence Campaign and a series of attacks by the Confederate armada on Republic fleets across the Outer Rim, especially on Falleen and Quell. These Separatist advances in the Outer Rim jeopardized the Republic's hold in crucial sectors, and civilian worlds like Ryloth and Mandalore suffered greatly from violence and the disruption of Outer Rim trade routes.
With the Jedi's attention focused on battling the Separatists, numerous crime syndicates and pirates took advantage of the war to expand their influence and criminal activities throughout the Outer Rim. Criminal groups and organizations like the Ohnaka gang, Hutt clans, Black Sun, and the Pyke Syndicate thrived because the Republic was preoccupied with the war effort. Groups such as the Zygerrian Slave Empire and Death Watch regained power in the Outer Rim with support from Count Dooku and the Separatists. These organizations created additional chaos in the Outer Rim, operating freely during the war. Moreover, as Republic forces were stretched thin across the Outer Rim, many Confederate planets, such as Geonosis, that were believed to be conquered and secured, rebelled and overthrew Republic occupation forces, allowing the Separatists to prolong the conflict.
Cato Neimoidia was invaded by Separatist forces before the Outer Rim Sieges. Felucia was the location of several engagements earlier in the war, including the destruction of a critical Republic medical station. After capturing Jedi Master Eeth Koth, Grievous advanced to Saleucami to establish a base, but the Republic thwarted his efforts. Furthermore, Mygeeto had been the site of prolonged campaigns throughout the war.
However, as the war went on, the Republic slowly managed to change the course of battle in the Outer Rim. The Confederacy experienced major setbacks after the destruction of the droid factories on Geonosis, and after the Republic repelled the Separatist Navy and Army at the Battle of Sullust and the Battle of Mon Cala. In addition, the Republic managed to secure victories on key worlds, such as at the Second Battle of Felucia.
Although the Republic seemed destined for victory in the war's final year, it would take longer than expected. The Separatists lost the majority of their droid factories and territory, pushing the CIS back to a few remaining redoubts in the Outer Rim during a Republic campaign known as the Outer Rim Sieges, although the campaign also saw fronts open in the Mid Rim and Colonies. Despite the Republic offensive, Grievous attempted to seize control of the shipyards on Anaxes, resulting in a protracted and bloody battle led by Admiral Trench, who moved his droid forces into the Coreward edge and launched a massive siege against the Republic shipyards. The battle concluded with a Republic victory and Trench's death.
During the campaign, the homeworld of Count Dooku, Serenno, became a focus for the Republic, but multiple attacks against both the D'Astan sector and the Serenno system itself failed to capture the world. At one point, a battle on Metalorn was fought. The Republic also besieged the Separatist-controlled world of Saleucami. For a time, the sieges reached a standstill.
Following the Battle of Anaxes, a new phase of the sieges began when Grievous initiated a counterattack. Grievous's counteroffensive pushed the Republic's forces, already stretched across the Outer Rim due to their offensive, beyond their breaking point outside of the Core. Indeed, while the Outer Rim had been a front of the Clone Wars since their beginning, the Akivan Norra Wexley, while walking through the aftermath of the Battle of Akiva, later recalled the CIS as "bringing" the war to the Outer Rim in its final years.
In these desperate final moments, the Republic and the Jedi Council deployed their generals throughout the Outer Rim to counter the Confederate assault. However, with the Jedi and most of the experienced officers away from the Core fighting in the sieges, Grievous exploited this vulnerability and launched a surprise assault on Coruscant with thousands of warships from the Separatist Navy.
The sieges continued until the final days of the Clone Wars. Battles that occurred during the late stages of the sieges included the Fourth Battle of Mygeeto, the Battle of Felucia, the Conquest of Kaller, and the Battle of Yerbana. Jedi Master Obi-Wan Kenobi and his former apprentice Jedi Knight Anakin Skywalker participated in the Outer Rim Sieges before being summoned for the Battle of Coruscant.
While the Confederacy had spread the Jedi and clone armies thin throughout the Outer Rim, the Republic continued to resist, shifting the momentum of the fighting in their favor and forcing the Confederacy into a defensive position. In the war's final days, the droid army and the Separatist fleet were severely weakened. In addition to ongoing losses in the sieges, the loss of Count Dooku and part of the armada at Coruscant further diminished the Separatist's ability to wage war in the Outer Rim and lowered morale among Separatist leaders, including Viceroy Nute Gunray, causing them to doubt the Confederacy's chances of winning the war.
After the rescue of Chancellor Palpatine, Grievous retreated to the Outer Rim world of Utapau, where he deployed the already severely depleted droid army across numerous systems in an attempt to push back the Republic. With Separatist forces spread thin across many Outer Rim sectors, it became increasingly difficult for the Jedi Council to track General Grievous, who had become the Head of State of the Separatist Alliance after Count Dooku's death, making him a high-priority target for the Republic to end the war. Republic politicians, including the Chancellor, were deeply concerned that the war would continue until Grievous was eliminated. However, days later, the Republic located the general on Utapau, and the subsequent battle and death of Grievous further destabilized the Separatist command structure. Following Order 66, the execution of the Separatist Council on Mustafar, and the deactivation of the droid armies, the sieges, and the war overall, came to an end.