The Gregorian Mission and Rochester
Justus was one of the missionaries sent from Rome to continue the work begun by Augustine of Canterbury among the Anglo-Saxons. He most probably arrived with the reinforcing party of 601, though some modern writers place him with the original mission of 597.
In 604 Augustine consecrated him bishop over a province including Rochester, making him its first bishop. A charter dated April 28, 604, attributed to King Æthelberht, records a grant of land near Rochester to his church; scholars continue to debate the document's authenticity, while some recent work argues it contains genuine early material.
Together with Mellitus, Justus signed a letter urging the Celtic bishops to adopt the Roman method of calculating the date of Easter, part of the mission's effort to bring the churches of Britain into common practice with Rome.
Exile and Restoration
When King Æthelberht died in 616, a resurgence of paganism threatened the young Christian community, and Justus, together with Mellitus, fled across the sea to Gaul, likely seeking the protection of the Frankish king Chlothar.
The exile proved brief: by 617 Justus had been reinstated in his bishopric under the new king of Kent.
Archbishop of Canterbury
In 624 Justus was raised to the archbishopric of Canterbury, becoming the fourth to hold the see. Pope Boniface V sent him the pallium confirming his office.
As archbishop he consecrated Paulinus as the first Bishop of York, who then accompanied the Kentish princess Æthelburg north to Northumbria, extending the mission's reach into that kingdom.
Relics & Shrines
Justus reposed on November 10, according to Bede most likely between 627 and 631. In the 1090s his remains were translated to a shrine placed beside the high altar of St Augustine's Abbey in Canterbury.
He was canonized in the period before the formal papal canonization process, and his feast is kept on November 10 across several Christian traditions. In the Orthodox Church he is honored among the Pre-Schism Western Saints and the Saints of the British Isles.