In one of those cutesy euphemisms, this feast has been renamed the 'Passion of John the Baptist' in the Ordinary Form.
The martyrology describes it thus:
"The beheading of St. John the Baptist, who was put to death by Herod about the feast of Easter. However, the 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. Silvester, near Campo Marzio, and honored by the people with the greatest devotion."This saint has a particular significance for Benedictines, as when he moved to Monte Cassino, St Benedict built a chapel in honour of St John the Baptist where previously had stood an altar to Apollo.
In many respects St John represents the two sides of the Benedictine charism - in his ascetic life in the desert, he points to the contemplative dimension; in his work preparing the way for Our Lord by calling the people to repentance, the active dimension.