 In 601 Peter led troops to the banks of the Tisza, to defend the Danube cataracts, which were vital to the Byzantine Danube fleet's access to the cities of Sirmium and Singidunum.The next year, in 602, the Antes began to invade the Avars' land, who were already on the brink of collapse due to the uprisings of several Avar tribes, one of whom even defected to the Byzantines.After being beaten back by the Byzantines under Maurice, the Avars shifted their focus to Italy, establishing diplomatic contact in 603, and attempting an invasion of North Italy in 610.