 Over the next decade, the Persians conquered Palestine and Egypt and Heraclius rebuilt his army, preparing for a new offensive, which he launched in 622. He achieved substantial victories over the Persians and their allies in the Caucasus and Armenia. In 627, he launched a daring winter offensive against Persia in Mesopotamia, and won a decisive victory at the Battle of Nineveh. This victory threatened the Persian capital city of Ctesiphon.
