 The Swiss Federation was alarmed by these developments, and in May 1530 a joint delegation from Bern, Fribourg, Zurich, Basel and Solothurn suggested to the Grand Council the abrogation of the 1526 alliance treaty in exchange for looser cooperation.The Grand Council rejected the offer and decided to oppose any attempt to restore Geneva to Savoy rule.On June 24, 1530, the Grand Council arrested a public prosecutor named Mandolia, who was a supporter of duke Charles III, and this irritated bishop Baume, who retaliated by arresting Genevan merchants in Gex, where he now resided.