 John went to France to recruit warriors to accompany him to Constantinople . Pope Gregory did not proclaim John 's expedition to the Latin Empire a crusade , but promised papal privileges granted to crusaders to those who joined him . During his stay in France , John was again an <unk> between local <unk> and signed a peace treaty between Louis IX of France and Hugh X of <unk> . He returned to Italy in late 1230 . John 's envoys signed a treaty with <unk> <unk> , <unk> of Venice , who agreed to transport him and his retinue of 500 knights and 5 @,@ 000 commoners to Constantinople in return for John 's confirmation of Venetian possessions and privileges in the Latin Empire . Shortly after John left for Constantinople in August , Pope Gregory acknowledged Frederick II 's claim to the Kingdom of Jerusalem . 
