In response, the armies in Egypt and Judaea declared Vespasian emperor on July 1. In his bid for imperial power, Vespasian joined forces with Mucianus, the governor of Syria, and Primus, a general in Pannonia. Primus and Mucianus led the Flavian forces against Vitellius, while Vespasian gained control of Egypt. On 20 December, Vitellius was defeated, and the following day Vespasian was declared emperor by the Roman Senate.