In 312, Roman Emperor Constantine was told in a dream to paint a cross on his army’s shields.
Based on that dream, he commanded his generals to slap crosses on
pretty much everything. If it went into battle, it had a cross on it.
And lo, when his army faced the rebel army that was twice the size of
his, his soldier guys smote them other soldier guys real bad and got all
pre-medieval on their butts; and Constantine did declare, “Hot
Damascus, it worked!” (Obviously, I am paraphrasing; I don’t speak
Latin.) So, Constantine remained emperor of Rome and a Christian, sort of.