The Accord of Winchester is the 11th-century document that establishes the primacy of the archbishop of Canterbury over the archbishop of York.
It originated in a dispute over primacy between Thomas, the archbishop of York, and Lanfranc, the new Norman archbishop of Canterbury, soon after the latter had taken office. The case was first heard by King William I at the old Saxon royal capital of Winchester at Easter (8 April) 1072, in the royal chapel in the castle. It was then heard at Windsor at Pentecost (27 May), where the final settlement was made, with William deciding in Lanfranc's favour, and formalised in this document.
This did not end the Canterbury-York dispute over the primacy, as it continued for a number of years after this.[1]