Gildas says that despite swearing an oath against deceit and tyranny, Constantine disguised himself in an abbot's robes and attacked two "royal youths" praying before a church altar, killing them and their companions. Gildas is clear that Constantine's sins were manifold even before this, as he had committed "many adulteries" after casting off his lawfully wedded wife. Gildas encourages Constantine, whom he knows to still be alive at the time, to repent his sins lest he be damned. The murders may relate to a sixth century cult in Brittany honoring the "Saints Dredenau", two young princes killed by an ambitious uncle.