Formed during the turbulent times known as the Age of Apostasy, the Sisters of Battle, or, as they are more formally known, the Adeptus Sororitas, number amongst the most stalwart defenders of Humanity. These female warriors form the Order Militant of the Ecclesiarchy, that vast organisation entrusted with the holy task of worshipping the Divine Emperor and preaching the tenets of the Cult Imperialis.

In the 36th Millennium, the power of the Ecclesiarchy was absolute, its authority virtually unchallenged though, for centuries, the Administratum had fought against this continued dominance. Much of the Imperium at this time was gripped by рге-apocalyptic gloom, as internal revolt, alien invaders and renegades took advantage of the turmoil wracking the galaxy. As world after world succumbed, entire populations turned to flagellation cults and horrifying acts of self-sacrifice in desperate attempts to rekindle the Emperor's love. Onto this bloody stage stepped the insane 361st High Lord of the Administratum, Goge Vandire. Originally known as the Daughters of the Emperor, the Adeptus Sororitas formed a bodyguard to Lord Vandire, protecting him from assassination by his enemies.

Vandire smashed the dominance of the Ecclesiarchy and amalgamated the position of Ecclesiarch and High Lord of the Administatum, becoming sole head of both organisations. Not since the days of the Horus Heresy had the Imperium seen bloodshed as was unleashed during Vandire's Reign of Blood. The horror was only ended when the Daughters of the Emperor learned the truth of his corruption and their leader, Alicia Dominica, beheaded Vandire in his own audience chamber.

The Imperium began the long process of rebuilding, and one of the first acts of the new High Lords was to pass the Decree Passive, which forbade the Ecclesiarchy from controlling any 'men under arms'. Never again would the Ecclesiarchy threaten the continued rule of the Administratum. The Daughters of the Emperor did not break this ban and thus were incorporated into the ranks of the Ecclesiarchy. Renamed the Adeptus Sororitas, they became true defenders of the faith and a very physical reminder of the power of the church.

The Sisters of Battle are trained to the highest levels with an unshakeable faith in the divinity of the Emperor. Their fanatical devotion and unwavering purify is a bastion against corruption, heresy and alien attack. Countless enemies of the Imperium have fallen before the righteous fury of the Adeptus Sororitas as they engage in Wars of Faith, bringing the Emperor's light to the dark recesses of the galaxy that have turned from the path of righteousness. Clad in ceramite power armour, they carry an awesome array of weaponry with which to smite their enemies, the wealth of the Ecclesiarchy ensuring that they are equipped with the best wargear the Imperium has to offer. The Sisters are incorruptible warriors, each dedicating her life to penitent worship and the rigorous training of mind, body and spirit.

One of the Adeptus Sororitas' greatest weapons is faith, and their zeal is a potent force, manifesting as divine inspiration that drives the Sororitas to unprecedented levels of performance. The Adeptus Sororitas often accompany the various priestly ranks of the Ministorum in their duties throughout the Imperium and many worlds have proven to be more responsive to the teachings of the Missionarius Galaxia with the intimidating presence of the Sisters of Battle in support of its preachers.