The Siege of Reillis was an early campaign of the Great Crusade. Waged when the Emperor and the young Horus fought side by side, the battle began when the Human fortified city of Reillis opposed assimilation into the Imperium. The anti-Imperial forces used secret tunnels to infiltrate the Imperial camp, sending swarms of shock troops across the Imperial Army lines. Unprepared and unarmored, the Emperor and Horus fought back to back until a Plasma blast sent the young Primarch reeling to the ground. The Emperor stood over the wounded Horus, refusing to give ground until reinforcements arrived and Imperial forces emerged victorious.

莱利斯围城是大远征的早期战役。当帝皇和年轻的荷鲁斯并肩作战时，战争开始了，当时人类设防的莱利斯城反对并入帝国。反帝国军队使用秘密隧道渗透帝国营地，派遣大批突击部队越过帝国军队的防线。帝皇和荷鲁斯没有做好准备，也没有穿上盔甲，他们背对背地战斗，直到等离子爆炸将年轻的原体击倒在地。帝皇站在受伤的荷鲁斯身边，拒绝让步，直到援军到达，帝国军队取得胜利。