enough to cause damage without penetrating the armour. Though iron became increasingly common, copper and bronze were also used, especially in iron-deficient areas. One example of a mace capable of penetrating armour is the flanged mace. The flanges allow it to dent or penetrate thick armour. Flange maces did not become popular until after knobbed maces. Although there are some references to flanged maces (bardoukion) as early as the Byzantine Empire c. 900 it is commonly accepted that the flanged mace did not become popular in Europe until the 12th century, when it was concurrently developed in Russia and Mid-west Asia. Maces, being simple to make, cheap, and straightforward in application, were quite common weapons. It is popularly believed that maces were employed by the clergy in warfare to avoid shedding blood (sine effusione sanguinis). The evidence for this is sparse and appears to derive almost entirely from the depiction of Bishop Odo of Bayeux wielding a club-like mace at the Battle of Hastings in the Bayeux Tapestry, the idea being that he did so to avoid either shedding blood or bearing the arms of war. In the 1893 work Arms and Armour in Antiquity and the Middle Ages, Paul Lacombe and Charles Boutell state that the mace was chiefly used for blows struck upon the head of an enemy. Eastern Europe Maces were very common in eastern Europe, especially medieval Poland, Ukraine, and Russia. Eastern European maces often had pear shaped heads. These maces were also used by the Moldavian ruler Stephen the Great in some of his wars (see Bulawa). The mace is also the favourite weapon of Prince Marko, a hero in South Slavic epic poetry. The pernach was a type of flanged mace developed since the 12th century in the region of Kievan Rus', and later widely used throughout the whole of Europe. The name comes from the Slavic word pero (перо) meaning feather, reflecting the form of pernach that resembled a fletched arrow. Pernachs were the first form of the flanged mace to enjoy a wide usage. It was well suited to penetrate plate armour and chain mail. In the later times it was often used as a symbol of power by the military leaders in Eastern Europe. Pre-Columbian America The cultures of pre-Columbian America used clubs and maces extensively. The warriors of the Moche state and the Inca Empire used maces with bone, stone