 He and the delegates of the Three Nations addressed a letter to Leopold I, pledging that he would never cede the Transylvanian fortresses previously held by German mercenaries to the Ottomans in March 1665.They also requested Leopold I to represent the Transylvanian interests during negotiations with the Ottomans, but Leopold's envoys signed a commercial treaty without mentioning Transylvania.The discontented Hungarian and Croatian aristocrats held meetings and started conspiring against Leopold I.