Every legion carried a signum. Not for decoration. A pole topped with an eagle or an open hand, raised above the dust and the din so that when the line broke and a soldier could see nothing else, he could find that one mark and know where he belonged. Lose the standard and you lost the unit. The Romans understood something we keep forgetting: a formation does not hold on discipline alone. It holds on a sign everyone can see.
Constantine knew this the morning he marched on the Milvian Bridge. The famous part is the vision, the words in the sky, in hoc signo vinces, by this sign conquer. Set the theology aside. Alignment from the gods was a tired trope long before Constantine claimed it, and every general who read a chicken's liver claimed the same. What mattered was what he did next. He took the sign and stamped it onto the shields. He mounted it on the standard itself, the labarum, and carried it at the head of the army. He did not merely have a vision. He converted a private conviction into a public mark his people could not lose in the chaos.
That is the whole move. Not the omen. The encoding. The reminder of the purpose of the initiative.