20th Army (Star League)

20th Army (SLDF) 2765.jpg
20th Army
Affiliation Star League
Parent Command Star League Defense Force

The Star League Defense Forces 20th Army was assigned to operations within the Rim Worlds Republic Territorial State.


Formed in the great expansion of the SLDF, the 20th Army replaced the IV and VI Corps who had defeated and garrisoned the Rim Worlds Republic since the Reunification War. At its peak the 20th consisted of twenty-five divisions which included seven BattleMech divisions, fifteen infantry divisions and thirty independent regiments. [1][2]

Due to Stefan Amaris's public loyalty and friendship with the young Richard Cameron and the fact that the Republic was almost totally peaceful while the other Periphery realms were on the verge of exploding into rebellion, as part of the Birthday Proclamations the future First Lord agreed to Amaris' request to withdraw the 20th Army from the Republic in 2755; the various divisions were transferred to bolster the other Territorial State armies[3] in the Draconis Combine and Lyran Commonwealth.[2] The withdrawal process started in 2755 and was completed by 2757.[4]

Despite being ordered to move to the Outworlds Alliance in 2760 the Twentieth Army remained near the Rim Worlds Republic and subcommands occasionally conducted reconnaissance-in-force operations into the Republic. This kept the combat units in fighting trim, but the army as a whole was unable to operate effectively. This was largely due to its subcommands being scattered over two member states. The Twentieth's refusal to relocate caused many problems for the SLDF Navy's Transportation Command's schedules as well. The Regular Army Command was also losing patience with the officers of the Twentieth, and if the Amaris Civil War hadn't occurred, these officers would likely have been reassigned.[4]

When the Periphery Uprising erupted, the divisions of the 20th initially attempted to stabilize tensions in the Territorial States as the Amaris backed Periphery Divisions attacked the SLDF garrison forces, suffering heavy losses in the process.[1] The 20th were still smarting from their ejection from the Republic, and seized the opportunity to try and prove their value when they were deployed as a rapid reaction force within the Outworlds Alliance; however, this determination manifested as over-eager recklessness and resulted in the 20th taking unneeded casualties, to the extent that SLDF Commanding General Aleksandr Kerensky issued a formal reprimand to the 20th. The total losses to the 20th in the Uprising amounted to eleven Divisions and eight Regiments, although three of the Divisions and one of the Regiments were disbanded rather than being destroyed in the battlefields of the Periphery.[2]

After the assassination of Richard Cameron, the divisions of the 20th joined the SLDF's assault on the Rim Worlds Republic and the campaign to recapture of the worlds of the Terran Hegemony. With less half its divisions surviving until the end of Operation Liberation, the 20th Army disbanded upon the collapse of the Star League; the bulk of its remaining divisions joined General Kerensky on his Exodus, although some elements of the 20th joined each of the Successor States other than the Free Worlds League.[1]

By mid-July 2772 the Twentieth Army was ready to take part in Operation CHIEFTAIN, the liberation of the Terran Hegemony. Serving alongside the Eighth Army and the Twelfth Volunteer Brigade, the Twentieth was a major component of the Second Army Group. The Second Army Group, Fifteenth Army Group and Twentieth Army Group made up Task Force Commonwealth, under the overall command of Admiral Joan Brandt.[5]


Rank Name Command
Commanding Officers of the 20th Army
General Gal Vlasic 2765[2]


Different per Unit.

Corps of the 20th Army[edit]



  • 7 BattleMech Divisions
  • 15 Infantry Divisions
  • 30 Independent Regiments


  • 2 BattleMech Divisions
  • 9 Infantry Divisions
  • 22 Independent Regiments

After two years of combat in the Periphery, the 20th Army had been reduced to just 43% of its original combat strength.[2]


  • 2 BattleMech Divisions[5]
  • 7 Infantry Divisions[5]
  • 20 Independent Regiments[5]


  1. 1.0 1.1 1.2 The Star League, p. 158, "Twentieth Army"
  2. 2.0 2.1 2.2 2.3 2.4 Historical: Liberation of Terra Volume 1, p. 45, "Twentieth Army"
  3. The Star League, p. 73, "Birthday Proclamation"
  4. 4.0 4.1 Field Manual: SLDF, p. 231
  5. 5.0 5.1 5.2 5.3 Historical: Liberation of Terra Volume 1, p. 120, "Operation CHIEFTAIN"
  6. Field Manual: SLDF, p. 232
  7. Field Manual: SLDF, p. 234
  8. Field Manual: SLDF, p. 236