(fratres jurati), persons who, by mutual oath, covenanted to share each other's fortune. Formerly, in any notable expedition to invade and conquer an enemy's country, it was the custom for the more eminent soldiers to engage themselves by reciprocal oaths to share the rewards of their service. This practice gave occasion to the proverb of sworn brothers or brethren in iniquity, because of their dividing plunder and spoil.