Meanwhile, Gabriel sent Hajdú captain András Géczi to Istanbul to express his gratitude for Ottoman support. Géczi made an agreement with Michael Weiss in Brassó, however, and asked for Gabriel's removal on behalf of the Three Nations of Transylvania in Istanbul in November. The Imperial Council of the Ottoman Empire accepted the proposal, and decided to replace Gabriel with Géczi. After the burghers of Brassó refused to surrender, Gabriel invaded Burzenland and captured seven Saxon fortresses in late March and early April 1612. The Diet of Transylvania urged the Saxons of Brassó to surrender in May, but the Three Nations delegates did not punish the noblemen who had fled to the town. Gabriel proposed a month later at the Diet that the principality should renounce the sultan's suzerainty, but his proposal was refused.