A statesman and bishop under the Merovingians, St. Arnulf was born in 580 and died in 640. His parents belonged to a distinguished Frankish family, and lived in Austrasia in the eastern section of the kingdom founded by Clovis.
In the school where Arnulf was placed as a boy, he excelled through his talent and his good behaviour. According to the custom of the age, he was sent in due time to the court of Theodebert II, King of Austrasia (595-612), to be initiated in the various branches of the government. Under the guidance of Gundulf, the Mayor of the Palace, he soon became so proficient that he was placed on the regular list of royal officers, and among the first of the kings ministers. He distinguished himself both as a military commander as well as in the civil administration, and at one time he had six distinct provinces under his care.
In due course, Arnulf was married to a Frankish woman of noble lineage, by whom he had two sons; Anseghisel and Clodulf. While Arnulf was enjoying worldly emoluments and honours, he did not forget higher and spiritual things. His thoughts often dwelt on monasteries, and with his friend Romaricus, also an officer of the court, he planned to make a pilgrimage to the Abbey of Lérins, evidently for the purpose of devoting his life to God.
However, in the meantime the Episcopal See of Metz became vacant. Arnulf was universally designated as a worthy candidate for the office, and he was consecrated bishop of that see around 611. In his new position he set the example of a virtuous life to his subjects, and attended to matters of ecclesiastical government. In 625 he took part in a council held by the Frankish bishops at Reims. With all these different activities, Arnulf still retained his station at the court of the king, and played a prominent role in the national life of his people.
In 613, after the death of Theodebert, he, with Pepin of Landen and other nobles, called to Austrasia Clothaire II, King of Neustria. When, in 625, the realm of Austrasia was entrusted to the kings son Dagobert, Arnulf became not only the tutor, but also the chief minister, of the young king. At the time of the estrangement between the two kings in 625 Arnulf, with other bishops and nobles, tried to bring about a reconciliation, but Arnulf dreaded the responsibilities of the episcopal office, and grew weary of court life.
About the year 626 he obtained the appointment of a successor to the Episcopal See of Metz, and he and his friend Romaricus withdrew to a solitary place in the mountains of the Vosges. There he lived in communion with God until his death. His remains, interred by Romaricus, were transferred about a year afterwards, by Bishop Goeric, to the basilica of the Holy Apostles in Metz.