Letter CXLV. To Leo Augustus 573 . (Asking him to help the church of Alexandria in appointing a good bishop in place of the murdered Proterius 574 .) 573     Marcian died in 457, and was succeeded by Leo of Thrace. 574     On Marcian’s death there had been a rising, in which Proterius had been brutally murdered, and a monk named Timothy Ælurus set up in his stead.