Warsmith

The title of Warsmith was an honorary rank held by the senior Astartes Captains who commanded the Grand Battalions of the Iron Warriors Legion. It was granted for exceptional skill and valour in carrying out the Legion's assaults and gave its bearer command over several of the IV Legion's companies, which were combined into the larger unit known as a Grand Battalion. After the end of the Horus Heresy, the title would later be the name given to the Chaos Lord who commanded each of the Iron Warriors' myriad warbands of Chaos Space Marines.

The Iron Warriors Legion of the 41st Millennium is organised into a number of large warbands known as Grand Companies, each commanded by a Chaos Lord who bears the title of Warsmith. Originally each Grand Company would have been similar in size and organisation, totaling approximately a thousand Space Marines, but now they vary in size enormously after ten millennia of battle and losses. The Warsmiths themselves are all extremely gifted in combat engineering, many maintaining a large contingent of slave-mechanicians to perform the more menial work.

It is uncertain how many Grand Companies there are at any given time. At the time of the Horus Heresy, the IV Legion had an added layer of organisation known as a Grand Battalion, which contained several Grand Companies and was commanded by a Warsmith. At the time of the Drop Site Massacre on Istvaan V there were at least twelve Grand Battalions in the IV Legion, although with the widespread deployment of many garrison forces in that era, it is impossible to be sure.