Wenceslaus was the son of Vratislaus I, Duke of Bohemia from the Přemyslid dynasty. His grandfather, Bořivoj I of Bohemia, was converted to Christianity by Saints Cyril and Methodius. His mother, Drahomíra, was the daughter of a pagan tribal chief of the Havelli, but was baptized at the time of her marriage. His paternal grandmother, Ludmila of Bohemia, oversaw his education, and at an early age, Wenceslas was sent to the college at Budeč.

In 921, when Wenceslas was about thirteen, his father died and his grandmother became regent. Jealous of the influence that Ludmila wielded over Wenceslas, Drahomíra arranged to have her killed. Ludmila was at Tetín Castle near Beroun when assassins murdered her on September 15, 921. She is said to have been strangled by them with her veil. She was at first buried in the church of St. Michael at Tetín, but her remains were later removed, probably by Wenceslas, to the church of St. George in Prague, which had been built by his father.

In 924 or 925, at about the age of 18, Wenceslas assumed leadership of the government and had his mother Drahomíra exiled. He then defeated a rebellious duke of Kouřim named Radslav. He also founded a rotunda consecrated to St. Vitus at Prague Castle in Prague, which exists as present-day St. Vitus Cathedral.

Early in 929, the joint forces of Duke Arnulf of Bavaria and King Henry I the Fowler reached Prague in a sudden attack that forced Wenceslas to resume the payment of a tribute first imposed by the East Frankish king Arnulf of Carinthia in 895. Henry had been forced to pay a huge tribute to the Magyars in 926 and needed the Bohemian tribute, which Wenceslas probably refused to pay after the reconciliation between Arnulf and Henry. Another possible reason for the attack was the formation of the anti-Saxon alliance between Bohemia, the Polabian Slavs, and the Magyars.

In September 935, a group of nobles allied with Wenceslas’s younger brother Boleslav plotted to kill him. After Boleslav invited Wenceslas to the feast of Saints Cosmas and Damian in Stará Boleslav, three of Boleslav’s companions, Tira, Česta, and Hněvsa, fell on the duke and stabbed him to death. As the duke fell, Boleslav ran him through with a lance.

According to legend, one Count Radislas rose in rebellion and marched against King Wenceslas. 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 Wenceslas, to avoid shedding innocent blood, challenged Radislas to single combat. As Radislas advanced toward the king, he saw by Wenceslas side two angels, who cried: “Stand off!” Thunderstruck, Radislas repented his rebellion, threw himself from his horse at the Saint’s feet, and asked for pardon. Wenceslas raised him and kindly received him again into favor.

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 St. 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 Wenceslaus Square will come to life, raise the army sleeping in Blaník, and upon crossing the Charles Bridge his horse will stumble and trip over a stone, revealing the legendary sword of Bruncvík. With this sword, King Wenceslaus will slay all the enemies of the Czechs, bringing peace and prosperity to the land.