In 1595, Sigismund Báthory staged an elaborate plot and had Aaron the Tyrant, voivode of Moldavia, removed from power. István Jósika (Báthory's chancellor and an ethnic Romanian) masterminded the operation. Ștefan Răzvan arrested Aron on charges of treason on the night of 24 April (5 May) and sent him to the Transylvanian capital at Alba Iulia (Gyulafehérvár) with his family and treasure. Aron would die poisoned by the end of May in the castle of Vinc. Sigismund was forced to justify his actions before the European powers, since Aron had played an active role in the anti-Ottoman coalition. Later on, in the same city of Alba Iulia, Wallachian boyars signed a treaty with Sigismund on Michael's behalf. From the point of view of Wallachian internal politics, the Treaty of Alba Iulia officialized what could be called a "boyar regime", reinforcing the already important political power of the noble elite. According to the treaty, a council of 12 great boyars was to take part alongside the voivode in the executive rule of the country.