Battle of Schrodinger VII
The fighting began when Necron forces assault the Ice World of Schrodinger VII. By the time the Black Templars under Helbrecht arrived the Necron Phaeron, Imotekh the Stormlord of the Sautekh Dynasty, had already shifted his armies into defensive configurations. Helbrecht's assault bogged down in a series of impeccably placed ambushes on the drop pod and Thunderhawk drop zones and Helbrecht and Imotekh met face to face on an ice bridge. They traded blows until Helbrecht collapsed but, instead of finishing him, Imotekh severed his right arm so he would always be reminded of the humiliation. The Black Templars retreated with Helbrecht, leaving Schrodinger VII in the Stormlord's hands.
Following a five year Crusade of penitence to atone for his defeat, Helbrecht made a pilgrimage to the Phalanx to pray at the hand of Rogal Dorn. There, the Chapter Master came to realize that the loss of his hand was symbolic of his Primarch's sacrifice and a sign from the Emperor. Helbrecht faith returns to him.