Solar Auxilia - Organisation: According to the measure of the Divisio Militaris of Terra, the Solar Auxilia cohorts were the definitive example of a heavy void infantry formation of the Excertus Imperialis during the Great Crusade. As such, they were fully trained and equipped to take on void war zones, hazardous planetary environments and operate both as "interface" troops (meaning transitioning from void to ground operations in combat conditions) and fight heavily-contested voidship boarding actions.Early Solar Auxilia forces were ranged in the standard fashion of a Principia Belicosa-required regimental structure, comprising a nominal 5,000 soldiers-at-arms under the formal command of an officer with the rank of "Legate-Colonel" and a dedicated staff and discipline cadre of around 300 officers and specialists. However, as the Great Crusade entered its expansion phase and the role of the Solar Auxilia in the wider war effort became more pronounced, and the demand for Solar Auxilia Pattern units increased, the Divisio Militaris High Command reconfigured the Solar Auxilia into larger, highly autonomous "cohort" formations.These "Solar Cohorts" were intended to be highly compartmental and owed something both to the structures employed by some of the elite forces of the Pan-Pacific Empire during the Wars of Unification as well as elements also used to organise the nascent Space Marine Legions.A Solar Auxilia cohort at muster would form a nominal fighting force of 120,000 individuals, with several thousand additional support staff of various types on permanent attachment to the unit, under the command of a general officer with the rank of "Marshal Solar." This would be broken down into a number of sub-cohorts, each with a nominal fighting strength of 1,200 under a "Legate-Commander," "Commander" or "Sub-Commander" depending on seniority and the sub-cohort's particular type.The fundamental building block of the Solar Cohort at the tactical level is the "tercio," a formation made up of three "sections" of Solar Auxilia, whose nature was defined by their weaponry and battlefield role. Tercios collectively could be assembled and deployed in a variety of ways and numbers to meet a particular strategic need. By far the most common tercio formation was the Infantry Tercio, made up of three lasrifle sections; each comprising twenty void-armoured, lasrifle-equipped infantrymen, commanded by a junior officer.Alongside these fought elite "Veletaris" tercios, each made up of three squads of ten veteran troopers equipped with augmented short-range weapons such as Volkite Chargers or Flamer units, and Fire Support Tercios, commanding three batteries each of three crew-served infantry support weapons platforms, of which the tracked Rapier type was the most common.Each tercio was itself a self-contained unit, and every Auxilia trooper within the tercios trained not simply as a front-line soldier, but also to be skilled in voidcraft, fundamental combat engineering, hostile environment survival and basic planetary exploration protocols. This particular combination of capabilities marked the Solar Auxilia out as a true elite among the mortal Human soldiery of the Imperium since the early days of the Great Crusade and remained a source of great pride within their ranks.