The Palatine Crusade was a military effort (or Crusade) by the forces of the Imperium to free the worlds of the Palatine Sector from secessionist rebels. The Crusade was headed by the Inquisitor Lord Ansgar and became noteworthy due to the miracle of Saint Celestine.
The war against the secessionists by the Sisters of Battle had ground to a stalemate on the world of Eurytion. Celestine was to be found at the head of the first attack wave assaulting the capitals defenses, leading Sisters Repentia. By all accounts Celestine was killed that day along with every other Repentia. As Celestine's body was put amongst the dead, her sisters saw her miraculously resurrect. Invigorated, the next day the assault on the city resumed with Celestine at its head. This time, the capital fell within scant hours and Celestine was declared the Crusades figurehead.
Inquisitor Ansgar, the Crusade's commander, believed the crusade would reach its conclusion at the capital world of the Palatine sector, but Celestine insisted first on taking a small, backwards planet named Sanctus Lys. Unknown to all bu ther, the world was home to the ancient Shrine of the Holy Heart, a place once visited by Saint Katherine. Amidst its shattered ruins, Celestine unearthed an ancient tomb and entered it alone. When she emerged, she was clad in golden shining armor and wielded a shining blade wreathed in sweet-scented petals. After this act, Inquisitor Ansgar and his conclave of Thorians declared Celestine a Living Saint. She then swept through the Palatine Sector, reclaiming it for the Emperor.