a powerful influence on the High Middle Ages concept of the rex justus (righteous king), a monarch whose power stems mainly from his great piety as well as his princely vigor. Referring approvingly to these hagiographies, the chronicler Cosmas of Prague, writing in about the year 1119, states: Several centuries later this legend was asserted as fact by Pope Pius II. Although Wenceslaus was only a duke during his lifetime, Holy Roman Emperor Otto I posthumously "conferred on [Wenceslaus] the regal dignity and title", which is why he is referred to as "king" in legend and song. The hymn "Svatý Václave" (Saint Wenceslaus) or "Saint Wenceslas Chorale" is one of the oldest known Czech songs. Traceable to the 12th century AD, it is still among the most popular religious songs in the Bohemian lands. In 1918, at the founding of the modern Czechoslovak state, the song was discussed as a possible choice for the national anthem. During the Nazi occupation, it was often played along with the Czech anthem. Wenceslaus's feast day is celebrated on September 28. On this day, celebrations and a pilgrimage are held in the city of Stará Boleslav, whereas the translation of his relics, which took place in 938, is commemorated on 4 March. Since 2000, the September 28 feast day has been a public holiday in the Czech Republic, celebrated as Czech Statehood Day. In legend According to legend, one Count Radislas rose in rebellion and marched against King Wenceslaus. The latter sent a deputation with offers of peace, but Radislas viewed this as a sign of cowardice. The two armies were drawn up opposite each other in battle array, when Wenceslaus, to avoid shedding innocent blood, challenged Radislas to single combat. As Radislas advanced toward the king, he saw by Wenceslaus's side two angels, who cried: "Stand off!" Thunderstruck, Radislas repented his rebellion, threw himself from his horse at Wenceslaus's feet, and asked for pardon. Wenceslaus raised him and kindly received him again into favour. A second enduring legend claims an army of knights sleeps under Blaník, a mountain in the Czech Republic. They will awake and, under the command of Wenceslaus, bring aid to the Czech people in their ultimate danger. There is a similar legend in Prague which says that when the Motherland is in danger or in its darkest times and close to ruin, the equestrian statue of King Wenceslaus in