Following the rise of Murad II to the throne, and the ascendancy of Manuel's hawkish son John VIII Palaiologos, the friendly Byzantine–Ottoman relations ended: Murad launched a brief siege of Constantinople in 1422, and began a long blockade of Thessalonica, which forced the Byzantines to hand it over to Venice in 1423. In a peace treaty concluded in February 1424, the Byzantines lost again most of the territories gained at Gallipoli, and were once more reduced to the status of tributary vassals.[30]