Eirene became the first female Byzantine autocrat by deposing and blinding her son Constantine VI. Her sole reign, however, should not be separated from her activities (and those of her advisors) during her regency of 780–790 and after 792. Most importantly, she secured the restoration of icons at the Second Council of Nicaea in 787, and the eunuch and patrikios Staurakios led a successful campaign against the Bulgars in Greece in 782. In other areas of foreign policy, however, she was less successful: the Franks gained control of portions of southern Italy, Arab raids pressed in on the east, and she was forced to accept terms from the Abbasid Caliph Harun al-Rashad in 798. Perhaps the most long-lasting repercussion of her assumption of sole power was the coronation of Charlemagne in 800. Up until then there had been just one empire, and one Christian emperor. Even though the Byzantines could not resist the Frankish king's assumption of the imperial Roman title, Charlemagne still needed recognition from the other Roman Empire for his title to be seen as valid. He sent emissaries to Constantinople to solicit Eirene's hand in marriage. While negotiations were still ongoing Eirene was deposed and exiled by Nikephoros, the logothetes tou genikou. It is interesting that in the eyes of later chroniclers Eirene's restoration of icons expunged the sin of the mutilation of her own son.
The seals and coins of Eirene duplicate her portrait on obverse and reverse, with the only difference being a control letter at the end of the reverse inscription. The portraits provide an opportunity to discuss the female imperial regalia. In particular, the empress’s crown is notable for its triangular projections and pendilia. The loros is the typical costume for empresses, as opposed to the chlamys for emperors, at least for the period before the mid-ninth century. Coins, however, do depict the empresses Eirene and Zoe wearing a chlamys, so this should not be seen as a rigidly maintained distinction.