The 12th Sector Army, also referred to as the 12th or the Twelfth Army, was a Sector Army within the Galactic Republic. During the Clone Wars, it operated as part of the Grand Army of the Republic in the northern region of the galaxy. Later, it transitioned to service under the Imperial Army of the Galactic Empire. Notably, one or more of its LAAT/i gunships were involved in a mission to Murkhana led by Dark Lord of the Sith Darth Vader and Moff Wilhuff Tarkin. The army's emblem featured a cerulean-skinned female Twi'lek wielding a spear.
Designated as the 12th Sector Army, and sometimes called the 12th or the Twelfth Army, this military formation was a Sector Army of the Galactic Republic during the period of the Clone Wars. Within the Grand Army of the Republic, Sector Armies numbered from the 7th to the 12th were deployed to the northern section of the galaxy, placing the Twelfth Army on planets like Felucia. As a Sector Army, the 12th was composed of four corps, totaling 147,456 clone troopers. As one of the twenty Sector Armies, the Twelfth Army was assigned a Haven-class medical station, specifically Felucia Medical Station HCTFF2, which was positioned in orbit around Felucia.
The symbol of the Twelfth Army consisted of a cerulean-skinned female Twi'lek carrying a spear, set within a dark circle against a yellow backdrop. During the Imperial Era, the Twelfth Army's LAAT/i gunships were decorated with this insignia.
From 22 BBY to 19 BBY, the 12th Sector Army saw action during the Clone Wars, a conflict fought between the Galactic Republic and the Confederacy of Independent Systems. Due to its location near crucial hyperspace routes, Felucia became a strategically important target for both factions, leading to its inclusion in the Twelfth Army's Republic campaign. Felucia was the site of numerous battles throughout the war, including the First Battle of Felucia, which involved the Republic's 7th Sky Corps, 104th Battalion, 501st Legion, and the Open Circle Fleet.
Following this, the Republic deployed Felucia Medical Station HCTFF2, which was assigned to the Twelfth Army, into orbit around Felucia, only to see it destroyed by the Confederacy. The Second Battle of Felucia once again featured the 104th and 501st, along with several clone tank divisions. Republic forces pushed the Separatists out of the Core Worlds and Colonies, pursuing them into the Mid Rim Territories and the Outer Rim Territories. Consequently, the 12th Sector Army targeted the Foundry of the Confederacy, which included factory worlds such as Boz Pity, Metalorn, Saleucami, and Felucia, during the Outer Rim Sieges. Jedi General Quinlan Vos and his unit engaged Separatist droid General Linwodo during the Siege of Boz Pity after a battle on Metalorn. Vos and his unit then took part in the Siege of Saleucami alongside other Republic forces, while the 327th Star Corps was involved in the Battle of Felucia.
The Twelfth Army continued its service under the Galactic Empire, the successor to the Republic, into the Imperial Era. Operating as part of the Imperial Army, elements of the Twelfth Army participated in a mission to Murkhana under the command of Dark Lord of the Sith Darth Vader and Moff Wilhuff Tarkin.