Phocas was a non-commissioned officer in the Roman army when he seized power, and was welcomed at first by many because he lowered taxes, which had been high during the reign of Maurice. But he also faced great opposition and was regarded by many as a usurper. He responded with extreme cruelty, allegedly killing thousands in an effort to keep the people in line.
He was no more successful as a military commander. The Balkans were soon lost to the invading Avars, who advanced as far as Athens. In the east, the Persian King Khusro II used Maurice's death as an excuse to break his treaty with the empire and attack Syria and Palestine. Soon, these lands were lost to the Empire.
In 610, several members of the government, seeing the empire collapsing around them and Phocas' cruelty increasing, sent an appeal to Heraclius the Elder, the powerful and popular Exarch of Carthage, asking him to aid them in deposing Phocas. His son, the future emperor Heraclius, then sailed for Constantinople. The army deserted to him and Heraclius was confirmed as Emperor by the senate. Heraclius personally executed Phocas.