Volume IIIA relates to the Soviet armed forces, mobilisation and war-economy during 1941. All significant Soviet weapon systems and combat squads used in the campaign are analysed, along with a contextual history. An assessment of each weapon system's inherent 'combat power' is provided, as well as attributes such as the relative anti-tank and anti-personnel values. Volume IIIA then focuses on the detailed Shtaty (TOEs) for all the Soviet land unit types fielded during 1941. All significant units in the RKKA (Red Army), VVS, VMF, PVO and NKVD are included; ranging from the largest mechanised corps and tank divisions, down to small mortar battalions and NKVD security companies. Also included are the most detailed Orders of Battle ever published on the Red Army, PVO and NKVD forces in June 1941. Even small and obscure units are included down to battalion and company level. Lastly, Volume IIIA examines in detail every unit's actual personnel and equipment in each of the USSR's Western Military Districts.

Volume IIB completes the Wehrmacht, and the German mobilisation and war-economy, in 1941. It includes the most detailed Orders of Battle ever published on the German Army (Heer), Luftwaffe and Waffen SS (across the whole Reich) in June-July 1941. Even the smallest and most obscure ground and air units are included, while the Luftwaffe OOBs include details on aircraft types and strengths. Also scrutinised are: the personnel and equipment assigned to combat-units in each army or reserve-force in all areas of the Reich; the ground and air unit reinforcements as well as those newly mobilised; the military personnel and equipment that became available in the Reich during 1941; the Replacement Army; the mobilisation process and resources used; the available replacements and those sent east; the logistical supply of the Wehrmacht (the varying Supply Distribution Efficiency); the Kriegsmarine forces in the east; and the Wehrmacht killed, wounded, missing/POW, unfit and recuperated casualties.

Operation Barbarossa: Volume IIA concerns the Wehrmacht. All the significant German weapon systems and combat squads used in the campaign are analysed using the quantitative methodology detailed in Volume I, along with the contextual history. An assessment of each weapon system's inherent 'combat power' is provided, as well as attributes such as the relative anti-tank, anti-personnel and anti-aircraft values. Volume IIA then focuses on the detailed Kriegstarkenachweisungen (KStN, or TOE) for German land units (including those in the West), as well as the unit's actual organisation and equipment. All significant units in the German Army (Heer), Waffen SS, Luftwaffe and security forces are included; ranging from the largest panzer divisions, down to small anti-aircraft companies, military-police units, Landesschutzen battalions, and rail-road and construction companies. In all cases the data is presented in detailed tables, using the weapon systems and combat squads previously analysed.

In June 1941 the Wehrmacht launched Operation Barbarossa: the attack on the USSR and the largest land invasion in recorded history. Operation Barbarossa: the Complete Organisational and Statistical Analysis, and Military Simulation focuses on 1941 - when the USSR came closest to defeat. It includes full analyses of the belligerents' armed forces, weapons, equipment, personnel, transport, logistics, war-production, mobilisation and replacements. The work employs a unique military simulation methodology, extending from the tactical to the strategic level, and applies this methodology to each of the belligerents. Volume I, the first of six volumes, is primarily concerned with the structure of this methodology, but uses many of the events and weapons from Operation Barbarossa as illustrative case studies. The complete work represents the most historically accurate, advanced and comprehensive analysis of the first six months of the largest and most decisive military campaign of WWII.