While the Persians proved largely successful during the first stage of the war from 602 to 622, conquering much of the Levant, Egypt, and parts of Anatolia, the ascendancy of emperor Heraclius in 610 led, despite initial setbacks, to the Persians' defeat. Heraclius' campaigns in Persian lands from 622 to 626 forced the Persians onto the defensive and allowing his forces to regain momentum. Allied with the Avars, the Persians made a final attempt to take Constantinople in 626, but were defeated there. In 627 Heraclius invaded the heartland of the Persians and forced them to sue for peace.