In heraldry, the labarum is a sacred military standard associated with Christian victory, imperial authority, and divine protection. Its meaning comes from the banner of Constantine the Great, traditionally bearing the Chi-Rho monogram formed from the first two Greek letters of Christ’s name. As a heraldic charge, the labarum unites the language of war and faith: it is a banner under which a ruler, knight, city, or institution claims to serve a holy cause. It can symbolize triumph through belief, lawful sovereignty, conversion, and the protection of Christ over armies or communities.

The labarum is closely tied to late Roman and Byzantine tradition, where imperial standards proclaimed both political command and religious allegiance. In later heraldry, it may appear as a vexillum, processional banner, or staff-mounted standard bearing the Chi-Rho, a cross, or other Christian sign. Its associations are therefore military, ecclesiastical, and ceremonial at once. It is especially suitable in arms connected with churches, Christian orders, military chaplaincies, seminaries, and institutions invoking Constantinian or early Christian heritage. Related forms also appear in ecclesiastical heraldry, where banners and processional standards express authority, patronage, and sacred mission.

Specific coats of arms using the term labarum are relatively uncommon, but the charge belongs to the broader heraldic family of banners, crosses, monograms, and Christian military emblems. Helpful visual and historical context can be found through Heraldry of the World’s banners category, Parker’s A Glossary of Terms Used in Heraldry, the Heraldry Society, and the College of Arms. In coats of arms, the labarum remains a dignified emblem of faith carried into public life, victory under sacred authority, and the union of courage with Christian conviction.