Georgetown should have told him that “In Hoc Signo Vinces” is Pall Mall’s slogan too.
It’s the ‘other’ IHS at Georgetown. First 3 letters of the Name “Jesus” in Greek. (Yes, Greek.) It’s that simple, contrary to the other dozen or so convoluted and inaccurate explanations on TV, internet and FR since the event. The “By this sign you shall conquer” thing has nothing whatsoever to do with the Society of Jesus founded by St. Ignatius of Loyola, obviously, centuries after Constantine.