[3] He was a dean (French: doyen) of Saint-Germain l'Auxerrois in Paris by 1278 and made archdeacon of Sologne and a canon of Orléans Cathedral in 1281.
Pierre had helped him negotiate the 1295 Treaty of Anagni, ending Franco-Aragonese fighting during the War of the Sicilian Vespers and bringing himself to papal attention.
Pierre de Mornay was obliged by the church to defend its position against the king, codified in the 1296 bull Clericis laicos.
Philip IV responded with an embargo against any export of gold or silver from France, effectively cutting Rome off from its French revenue while the Colonna family revolted against Boniface.
Boniface yielded over a series of bulls, threatening excommunication while effectively pledging to approve reasonable taxation in Ineffabilis amor, allowing "voluntary" "donations" from a country's clergy without papal approval during times of emergency in Romana mater ecclesia, and finally capitulating entirely to Philip's position in the 1297 Etsi de statu and canonization of Louis IX.