The fifteenth day of June.
- 1053: The army of Pope Leo IX is defeated by the Normans at the Battle of Civitate
- 1520: Pope Leo X issues the papal bull Exsurge Domine, threatening Martin Luther with excommunication unless Luther recants 41 points of doctrine culled from his writings within 60 days. Luther responds with On the Freedom of a Christian.
- Augustine of Hippo's feast in many Eastern Orthodox Churches
- Saint Vitus (observed with Sts. Modestus and Crescentia), patron of actors and epileptics
- Saint Landelin (7th century)
- Saint Edburga of Winchester (d. 960)
- Saint Germaine Cousin, (d. 1601), patron of shepherdesses and of victims of child abuse