He served as interim Grand Master of the Knights Hospitaller after the death of Geoffroy de Donjon in 1202.
The French historian Augustin Chassaing wrote about Mirmande: "This is an interesting and very rare chance to meet the starting point in the West of an Hospitaller, called to command, thirty years later in the East, one of the most important places of war of the order.
"[1] The first mention of Pierre de Mirmande is in a charter dating from May 1163 when he entered the Order at the Saint John's commandery of Le Puy-en-Velay.
De Mirmande became the Grand Master ad interim and directed the Order in the East in his absence.
[7] It's in this context that on 23 March 1203, Pierre de Mirmande left on a diplomatic mission alongside Philippe du Plessis, Grand Master of the Knights Templar and Soffredo Gaetani, legate of pope Innocent III.