The beheading of St. John Baptist, who was put to death by Herod about the feast of Easter. However, his solemn commemoration takes place today, when his venerable head was found for the second time. It was afterwards solemnly carried to Rome, where it is kept in the church of St. Sylvester, near the Campus Martius, and honoured by the people with the greatest devotion.Devotion to St. John the Baptist has been widespread for centuries. "A homily on the Ascension that same year (May 26, 1960) afforded Pope John XXIII the opportunity to assert that it may be piously believed that St. John the Baptist and St. Joseph were bodily assumed into Heaven at the time of our Lord's Resurrection"
Source: pre-1960 Martyrology
For information on this feastday, please see my post entitled: Martyrdom of St. John the Baptist.