

The remnants of the three regiments, some 3,500 Guardsmen, were formed into a single regiment, the Tanith First and Only, with Gaunt promoting two members of a delegation sent to confront him, Corbec and Rawne, into its colonel and major respectively. In the attack that followed, Tanith and the majority of its people were immolated. Gaunt quickly decided that Tanith could not be saved, and, instead of allowing the guardsmen to engage in a futile defense of their homeworld, ordered as much of the men and equipment evacuated off-planet as possible before the Chaos ships arrived.

On the very night of the regiments' Founding ceremony, however, disaster struck: a Chaos splinter fleet that had slipped through the Imperial Navy blockade arrived in the Tanith system, which was practically defenseless. Originally, the people of Tanith were tasked to contribute three regiments for the Imperial Guard: the 1st, 2nd and 3rd of Tanith - totalling 6,000 men and a small number of vehicles and artillery pieces, to be commanded by Colonel-Commissar Ibram Gaunt. During the Sabbat Worlds Crusade, the planet Tanith was called on to raise regiments for the Astra Militarum for the first time in its history.
