13th Army Group (Star League)

Thirteenth Army Group
Formed 2765
Affiliation Star League
Parent Command Star League Defense Force (2765)[1]


The Thirteenth Army Group was the Star League Defense Force Army Group formed to command the invasion of the Outworlds Alliance during the Periphery Uprising.[1]


Star League Era[edit]

In common with the other SLDF Army Groups, the Thirteenth Army Group was commanded by a General-rank officer who answered only to the SLDF High Command and the First Lord of the Star League.[1] In 2765, three additional armies based in Inner Sphere military regions were deployed forward into the Periphery to support the Eighteenth Army, which was under siege in the Alliance, as large numbers of Secret Army units raised by Stefan Amaris bolstered the local rebel forces.[2] The Thirteenth Army Group was formed to take overall command of all four armies operating in the Outworlds Alliance[1] which consisted of two armies redeployed from the Draconis Combine Military Region plus the Twentieth Army, which had originally been based in the Rim Worlds Republic before being recalled, and the Eighteenth Army. The widely-dispersed deployment of the Eighteenth Army had helped it survive the initial attacks, as it was difficult for the rebels to concentrate forces to overwhelm the scattered SLDF commands, even with units from the Alliance Military Corps overtly assisting the rebels, although the Eighteenth Army had buckled under the weight of the determined attacking forces.[2]

The Fifteenth Army forced its way through the Cerberus Province and Traders Domain, aiming for the Blommestein Province, while the Sixteenth Army attacked the Alpheratz and Ramora Provinces, aiming to relieve the Eighteenth Army garrisons in the Onverwacht Province. Both were infantry-heavy armies, which made them ideal for holding conquered worlds, but also made them vulnerable to attack, and each suffered heavy losses. The Twentieth Army was the most aggressive of the invading armies, determined to live down the perceived stigma of being withdrawn from the Rim Worlds Republic; after pushing through the Baliggora and Ramora Provinces to capture Alpheratz, the capital world of the Alliance, in December 2765. The Twentieth then acted like a rapid reaction force, but often acted impulsively and without gathering intelligence first. They also left positions under-garrisoned and were drawn into a number of traps, taking losses in manpower and equipment needlessly. This drew criticism from Commanding General Aleksandr Kerensky, although by the start of 2767 the Thirteenth Army Group had three-fifths of the Alliance back under Star League control. Plans had been prepared to finish the campaign for the Alliance by the end of 2767, but news of the Amaris Coup led to General Kerensky ending military actions against the rebels.[2]

The Thirteenth Army Group is not recorded as having taken an active part in Operation CHIEFTAIN;[3] at least three Army Groups were active during CHIEFTAIN but serving as training commands and not listed on the order of battle (the Sixteenth, Eighteenth and Twenty-third Army Groups)[1][3] and it is unclear whether the Thirteenth was still active during the campaign to free the Terran Hegemony, or if it had been disbanded as an organisation after the campaign against the Alliance ended.

At its peak, the Thirteenth Army Group numbered 110 divisions and 78 independent regiments - a total of 492 BattleMech regiments and 585 conventional regiments. During the course of the Periphery Uprising the losses taken by the Thirteenth amounted to 37 divisions and 19 independent regiments, with 10 divisions and 3 regiments taking sufficient damage during the conflict to see them disbanded, for a total of 445 regiments.[2]


Rank Name Command
Commanding Officers of the Thirteenth Army Group



Composition History[edit]


Thirteenth Army Group (30 BattleMech Divisions, 65 Infantry Divisions, 84 independent regiments)[2]


  1. 1.0 1.1 1.2 1.3 1.4 Historical: Liberation of Terra Volume 1, p. 37, "Military Regions and Army Groups"
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Historical: Liberation of Terra Volume 1, p. 97, "The Outworlds Campaign"
  3. 3.0 3.1 Historical: Liberation of Terra Volume 1, p. 120-121, "Operation CHIEFTAIN Star League Defense Forces Order of Battle"