In 1012 an Irish pilgrim following the overland pilgrimage route to Jerusalem was murdered by the inhabitants of Stockerau near Vienna on the false suspicion that he was a Czech spy. Following his death, miracles began to occur and he came to be venerated as a saint by the local people. In 1015 renown of this new saint came to the attention of the ruler of this frontier region of the Eastern March of Bavaria, the Babenberg margrave, Henry I. The margrave appropriated the incorrupt body of the martyr and took it to his stronghold at Melk. The spiritual power of the new saint was a valuable asset for Henry, a marcher lord in the process of consolidating his power base in this volatile, frontier region. This article considers the role of the cult of St. Coloman in affirming Babenberg power and authority and in the process helping to shape a new identity for the region that would become Austria. It presents a new edition and English translation of the Passio et Miracula S. Cholomanni, a composite work of hagiography from the eleventh and twelfth centuries and the principal source for the cult of St. Coloman.