Regent and empress
When Leo IV died on 8 September 780, rumors were circulated claiming that he had died of a fever after putting on the jeweled crown from the Great Church that had been dedicated by either Maurice (r. 582–602) or Heraclius (r. 610–641). It is uncertain whether Irene herself had promoted this rumor, perhaps in an attempt to smear her iconoclast husband's memory. Quickly after Leo IV's death, Irene became regent for their nine-year-old son Constantine VI and secured the throne for him by crushing the usurpation plots in favour of Leo's brothers in the following month.
In October, only six weeks after Leo IV's death, Irene was confronted with the conspiracy led by a group of prominent dignitaries that sought to raise Caesar Nikephoros, a half-brother of Leo IV, to the throne. Irene had Bardas (the former strategos of the Armeniac Theme), Gregory (the logothete of the dromos), and Konstantinos (the count of the excubitors) scourged, tonsured, and banished. She replaced all of them with dignitaries who were loyal to her. She had Nikephoros and his four brothers ordained as priests, a status which disqualified them from ruling, and forced them to serve communion at the Hagia Sophia on Christmas Day 780. On the same day, Irene returned the crown her husband had removed as part of a full imperial procession. Possibly hoping to placate supporters of her husband's family, Irene is reported to have proposed that Leo IV's sister Anthousa should join her as co-regent, but Anthousa is said to have rejected the offer.
From the beginning, Irene seems to have taken more power for herself than was traditionally expected of female regents. Her earliest coins depict both herself and her son Constantine VI on the obverse, listing them as co-rulers rather than as ruler and regent. Furthermore, Irene is shown holding the orb, not Constantine, and only Irene's name is listed on the obverse of the coin, with Constantine VI's name only listed on the reverse, the less important side. Also, in all orders, both oral and written, Irene's name took precedence over her son's name, and she signed her orders in the name of the emperor in her own right and her name took precedence in the oath of allegiance. Apart from that, she did not allow Constantine any voice in public affairs. At the same time, Irene appears to have been well aware that her position as regent was insecure. The last female regent of the Byzantine Empire had been Empress Martina, who had only managed to survive as regent for less than a year before her tongue was cut out and she was exiled to the island of Rhodes. Most people were probably expecting that Irene's reign would come to a similarly swift and bloody end.
In 781 Irene accused the stratēgos of Sicily, Elpidius, of participating in the conspiracy involving her brother-in-law Nikephoros. The military in Sicily prevented his arrest, so Irene sent a fleet which succeeded in defeating the rebels. Elpidius fled to Africa, where he defected to the Abbasid Caliphate. The fact that this revolt appears to reflect personal ambition or political conflicts centring in the capital, rather than local separatism, demonstrates the loyalty of the island to the Empire.
After the success of Constantine V's general, Michael Lachanodrakon, who foiled an Abbasid attack on the eastern frontiers, a huge Abbasid army under Harun al-Rashid invaded Anatolia in summer 782, reaching Chrysopolis on the Asiatic side of the Bosphorus The stratēgos of the Bucellarian Theme, Tatzates, defected to the Abbasids, and Irene had to agree to pay an embarrassing annual tribute of 100,000 dinars to the Abbasids.
In 783, Staurakios, eunuch and logothete of the dromos under Irene, led a successful campaign against the Sclaveni of Thessaly, Greece and the Peloponnese, returning with booty and captives. In 784, Irene capitalized on Constantine V's successes in Thrace and ordered Veria and Anchialos to be "rebuilt".
By 786, Harun, then the Abbasid Caliph, had made Raqqa his residence in order to secure control over the frontier. In 797/798, the Abbasids were said to have reached the Bosphorus again, but agreed to negotiate with the Byzantines due to the threat of the Khazars in the north. Nonetheless, he engaged in a campaign of assiduously strengthening the frontier with new districts and strongholds (al-Awasim), specifically from Cilicia through Germanikeia to Melitene. There was significant settlement and economic activity in the frontier region by the Abbasids, which was not typical in the time of the Umayyad Caliphate. Harun proved to be a capable commander and Irene and her successor Nikephoros I struggled to effectively resist his campaigns.
