At the same time, the "tagmata" were extensively employed in campaigns during this period: their participation is attested at least for Constantine V's 773 campaign against the Bulgars, and during the Abbasid invasion of Asia Minor in 782. Indeed, the historian John Haldon remarks that the retention of the "tagmata" by Irene, despite their iconoclastic bias, is testament to their effectiveness as a field force. The "Scholae" and the Excubitors nevertheless continued to play an active political role in the events of the following decades: in 792, they attempted to overthrow Irene's son, Constantine VI (), after the disastrous Battle of Marcellae against the Bulgars, and in 797, their support was crucial for Irene's overthrowing her own son and replace him as sole ruler; and again, the two "tagmata" were crucial in the deposition of Irene herself in 802.