Maurice builds more fortifications along the Danube frontier, separating the Empire from the realm of the Avars and Slavs.
Nothing is known of the early life of the imperial general Comentiolus, except that he hailed from Thrace.
He first appeared in 583, as an officer (scribon) in the Excubitores, the imperial bodyguard, when he accompanied an imperial embassy to Bayan I, the khagan of the Avars.
According to the historian Theophylact Simocatta, he enraged the khagan with an outspoken statement, and was briefly imprisoned.
It is likely that the close trust he shares with Maurice dates from the latter's time as commander of the Excubitores, before his ascension to the throne.
Throughout his career, Comentiolus will be loyal to Maurice, and the Emperor will watch over his protégé's career.
The next year, after a truce with the Avars had been arranged, he had been appointed in charge of a brigade (taxiarchia) operating against the Slavic tribes that raided Thrace and had penetrated as far as the Long Walls of Anastasius, Constantinople's outer defensive system.
Comentiolus had defeated them at the river Erginia, near the Long Walls.
As a reward for this success, he had been appointed magister militum praesentalis in 585.
On this occasion, or perhaps a bit later (possibly in 589), Comentiolus had been raised to the supreme title of patricius.
In the summer of 585, he had again defeated a large force of Slavs, and in 586 he had been placed in charge of the war against the Avars, after they broke the treaty.
In 587, Comentiolus assembles a ten thousand-strong army at Anchialus and prepares an ambush for the Avar khagan in the Haemus mountains, but it fails.
