The role of the clergy at a medieval wedding was simply to bless the couple. It wasn't official church policy until the council of Trent in the 15th century that a third party (i.e., a priest), as opposed to the couple themselves, was responsible for performing the wedding. In the later medieval period, the wedding ceremony moved from the house of the bride to the church. It began with a procession to the church from the bride's house. Vows were exchanged outside the church (by the way, the priest gave the bride to the groom) and then everyone moved inside for Mass. After Mass, the procession went back to the bride's house for a feast. Musicians accompanied the procession.