Roman warfare in the Balkans led to an unforeseen disaster. Maurice had re-established Roman supremacy on the eastern frontier and gained striking successes against the Avars and Sclaveni in the last decade of the sixth century. This had not been achieved without cost. During the campaigns Maurice had been forced by financial stringency to reduce military pay (Theophylact 7.1.8). We may infer that the empire's tax revenues were no longer sufficient to sustain the burden of frontier defense and aggressive campaigning, and in Thrace, in contrast to Mesopotamia, there was no prospect of supplementing revenue by any significant war spoils (see pp. 472–5). In 602 the field army of Thrace was required to conduct a winter campaign against the Slavs, an operation which promised military success according to Maurice's own strategic theories but offered scant hope of booty and little prestige (Maurice, Strategikon 11.4.82ff.). The soldiers showed signs of growing rebelliousness, defied repeated orders from the emperor, and pressed initially for better conditions of service (John of Nikiu 102, 10–11). Fierce winter conditions were compounded by renewed orders from the emperor to attack the barbarians north of the Danube, without provisions from the commissariat, in the expectation that the troops would live off the land they were occupying. A delegation from the ranks pleaded that they should be allowed home for the winter (Theophylact 8.6.2–10). It is clear that Maurice's commanders in the field thought the imperial orders to be hopelessly misjudged, but had no option except to insist that the campaign continue. The troops assembled without their officers over two successive days and brought their protests to a head by raising one of their delegates, the centurion Phocas, on the shields of his fellow-soldiers in the ritual traditionally associated with the creation of a new emperor (Theophylact 8.7.1–7).
Theophylact's detailed account of the fall of Maurice forms the climax to his history and is likely to have been the seed from which his whole work was conceived. At some date, probably early in Heraclius' reign, he had been invited to deliver a eulogy of Maurice, which had moved his audience to tears (Theophylact 8.12.3–7). The narrative which survives in the history not only contains elements that were surely drawn from this panegyric, but also shows numerous traces of Theophylact's own careful enquiries into the course of events. This is the most revealing analysis of a major political event in Constantinople since the accounts of the Nika riot of 532. The crisis developed rapidly amid a complex interplay of forces: the emperor Maurice and the members of his family; the claims and political credibility of a wealthy rival, Germanus, whose daughter had married Maurice's son Theodosius; Phocas and his close-knit group of military officers, which had led the mutiny on the Danube; the urban mob at Constantinople; and the only organized groups in the city that could in any way represent or articulate the people's wishes, the circus factions. The Blues, and especially the Greens, were to play a larger role in the fall of Maurice than in any previously attested political context. It appears mistaken to argue that they were motivated by specific political allegiances or objectives. They were, nevertheless, a major force, and the events of the coup made it clear that the circus factions could be a potent political force in the cities of the empire at the beginning of the seventh century.13
As rumors of the mutiny spread among the population, Maurice's general Peter brought the news to the capital. Maurice attempted to reassure his subjects by staging chariot-races in the hippodrome, and used the opportunity to seek the support of the Greens and the Blues. The registered partisans, almost 2,000 in number, were dispatched to garrison the Theodosian Walls, while Phocas and his troops gathered outside the city. The mutineers began negotiations by approaching Maurice's son, Theodosius, and Theodosius' father-in-law Germanus, and offered loyalty if either of these would oust Maurice and take over the empire. The compromised Germanus was summoned before Maurice and ordered to take his own life, but fled first to his house on the Mese and then, with his armed followers, to the nearby church of the Virgin, built by Theodosius II's minister Cyrus. By nightfall Germanus and his men had moved to the sanctuary of St Sophia itself, where the rebellion came to a climax. Enormous crowds gathered outside the church and began to chant insults against the emperor, and the partisans of the factions abandoned their positions on the walls to join the mob. As the rioting people burnt down the grand house of Maurice's praetorian prefect of the East, Constantine Lardys, the emperor, disguised as a commoner, took flight with his wife, other family members, and the praetorian prefect to the church of St Autonomus on the south side of the sea of Marmara. His son, Theodosius, and Constantine were then instructed to escape from the empire and seek help from Khusro (Theophylact 8.7.8–9.12).
For a brief moment it was uncertain whether Germanus or Phocas would take charge after Maurice's departure, but the hostility of the Green faction to Germanus decided the issue, and a delegation from the Greens prevailed on Phocas to advance to the Hebdomon, at the seventh milestone from the city center, where he was inaugurated at the great church of John the Baptist, a traditional location for the proclamation of new emperors. Phocas entered the city on November 25, 602. Amid the chariot races which were staged in celebration, largesse was showered on the members of the circus factions and on Phocas' own military following. Two days later Maurice and his entourage were arrested and brought back to Chalcedon, but the rumor that he was still alive led to rioting in the hippodrome, during the coronation ceremony of Phocas' wife Leontia, between the Greens, who had been the main instruments of Phocas' coup, and the Blues. Another close associate of Phocas, Lilius, was ordered to do away with Maurice and his sons. Their bodies were thrown into the Bosporus before huge crowds of onlookers, while the head of Maurice was brought back and displayed to Phocas' troops at the Hebdomon outside the city. The only family member to avoid the immediate slaughter was the emperor's eldest son Theodosius who had escaped as far as Nicaea, but was then reported to have returned with Constantine Lardys to the Church of St Autonomus, where it was alleged that he had been killed by one of Phocas' leading officers, Alexander (Theophylact 8.9.13–12.12).