18 July - Frederic of Utrecht was born around 780. He was sent to Utrecht by his mother, the grandson of the King of the Friesians, and was elected bishop there in 820/826, despite his reluctance, at the behest of the Western Emperor Louis the Pious, with whom he quarrelled a few years later.

In 829 he attended the Council of Mainz and continued the evangelisation of Friesland. It was to him that the Benedictine monk Raban Maur dedicated his Commentary on Joshua in 834.

The second marriage of the aging Emperor Ludwig the Pious with the very young Judith of Bavaria (twenty years his junior) in 819 created tensions. According to custom, the sovereign planned the division of his empire between his three sons in 817. The birth of a fourth son in 823 changed the situation. The empress intrigues that her son should also receive a share of the empire while leading a frivolous life away from her old husband.

In 829 in Worms, the emperor established a new division of his empire in 829, which was particularly favourable to his last son. The elder sons rebelled. Lothaire, the eldest son to whom the imperial succession was promised, claiming to want to settle the dispute peacefully, appealed to Pope Gregory IV, who came from Rome to the banks of the Rhine to meet the belligerents. Meanwhile, the emperor was abandoned by his allies and even dismissed in favour of Lothaire in 833. Judith was relegated to a convent where she was condemned to take the veil. However, the Emperor was reinstated by the Council of Thionville in 835 and Judith, relieved of her forced vows by the Pope, was ordered to find her husband.

During the conflict, the bishop of Utrecht, perhaps doubting the legitimacy of the two children she had given to the crown, and faithful to the pope, vehemently criticizes the dissolute life of the empress and supports Lothaire. He was assassinated - perhaps on the order of the sovereign - on July 18, 838 at the end of the Mass he was celebrating.