"Constantine was converted to Christianity by a vision that came to him on the eve of the battle of Milvian Bridge: "He saw with his own eyes, up in the sky and resting over the sun, a cross-shaped trophy formed from light, and a text attached to it which said, 'By this sign, conquer' ". Soon the cross would morph from being a hated symbol of Roman brutality into the universally recognizable logo of the Holy Roman Empire. Within a century, St Augustine would develop the novel idea of just war, trimming the church's originally pacifist message to the needs of the imperial war machine."