Pilgrims from the Calixis Sector and beyond, the men and women of the Landrian Milita (most of whom are not natives of the Hive World of Landunder) have embraced the teachings of the saint and journey to the Jericho Reach to complete his holy work and fight in his name.
During the early years of the Achilus Crusade, the Landrian Militia first began appearing within Lord Militant Tiber Achilus' fleets, arriving on pilgrim vessels, supply transports and even Rogue Trader ships, eager to fight for the Imperium.
These pilgrims believe that they have joined the ongoing Margin Crusade, and the vast majority are completely unaware that they have thrown their efforts into another conflict entirely.
Though no clear cause of this exodus has been uncovered, some believe that the saint himself appeared to his followers on the eve of the crusade and told them they must join in this endeavour for the sake of the Calixis Sector which Saint Drusus watches over.
Whether this is true or not, the pilgrimage of the Landrian Militia has become a steady flow pouring into the Reach by whatever means it can find.
At first both Imperial commanders and the adepts of the Departmento Munitorum paid little heed to the Landrian Militia and their desire to fight. Outside the official structure of the Astra Militarum and unclaimed by the Adeptus Ministorum (which already had several "mob-regiments" of Frateris Militia attached to the crusade) they were used largely for labour in the creation of the Iron Collar, the ring of planetary fortresses that served as the headquarters for the Imperial war effort in the Reach.
It was not until the first forays against the T'au, when Lord Commander Sebiascor Ebongrave decided to create a company from the workers on Spite, that their true worth was realised. Fanatical in combat and filled with an intense hatred of their enemies, they proved themselves time and again in battle.
Better yet, there seemed to be endless numbers of them arriving through the gate, an untapped source of reinforcements which first Achilus and then later his successor as lord militant, Solomon Tetrarchus, was more than happy to exploit.
Grudgingly, the Departmento Munitorum dubbed this new formation the "Landrian Militia" (though to date the regiment's actual strength and assets have never been fully recorded) and assigned the title to all formations of Landrian pilgrims regardless of their actual numbers, world of origin, or where they fought.
Wherever a soldier travels within the Reach, he is likely to see groups of Landrian Militia in their tattered brown robes carrying their battered lasguns and scavenged weaponry, usually gathered together in silent prayer or listening to the rantings of one of their Confessors.
Primarily used as auxiliary and support troops for more elite Astra Militarum formations, they nevertheless perform well, often fighting better than more "traditional" Astra Militarum regiments.
Many Imperial commanders have come to favour them as shock troops, sending them in with the first waves of an assault (often assigning Commissar cadets to them to earn some hard-won experience in battle) and relying on their fanaticism to break the line before following up with more disciplined troops to press forward the attack or hold the ground.
For their part, the troops of the Landrian Militia don't seem to mind the role they have to play in the crusade, eagerly selling their lives for the glory of their saint and arriving in their thousands every solar month to replace those that fall in Drusus' name.
- Deathwatch: The Achilus Assault (RPG), pp. 29-30