Barbatio Barbatio ( died AD 359 ) was a Roman general of the infantry under the command of Constantius II . Previously he was a commander of the household troops under Gallus Caesar , but he arrested Gallus under the instruction of Constantius , thereby ensuring his promotion on the death of Claudius Silvanus . In 359 , both he and his wife Assyria were arrested and beheaded for treason against Constantius , possibly as part of a plot by Arbitio , a senior cavalry commander , and another exponent of the forms of scheming and political intrigue that became such a part of the later Roman Empire . Fall of Gallus . Barbatio , a soldier of unknown origin , began his rise when he was appointed to command the household troops of Caesar Gallus , a cousin of the Emperor Constantius II . Constantius was a man of uncertain temperament , highly suspicious of possible rivals , who had been responsible for the execution of many members of his own family after the death of his father Constantine I in 337 . Barbatio betrayed his position of trust , beginning a whispering campaign against Gallus , which led to his downfall in 354 . According to the account of the historian Ammianus Marcellinus , " Barbatio , after surrounding with armed men all that part of the palace which lay outside of the walls , entered as night was falling , stripped the Caesar of his royal apparel , and dressed him in the tunic and cloak of a common soldier , assuring him , however , with repeated oaths that he had the emperor ' s authority to tell him that he would suffer nothing further . " . Contrary to these assurances , Gallus was taken to Pola , where he was beheaded , and his face mutilated after execution . For his part in the affair , Barbatio was awarded by Constantius with a series of promotions , making him commander of the infantry in Gaul after the death of Claudius Silvanus in 355 . According to Ammianus , Barbatio was a man of " rough manners and vaulting ambition , who incurred general hatred by his treacherous betrayal of Caesar Gallus " . Having betrayed one Caesar , he soon found himself in a position to attempt to betray another . Barbatio and Julian . Not long after the death of Gallus , Constantius summoned Flavius Claudius Julianus , the dead man ' s scholarly half - brother , from his studies in Athens to the royal court in Milan . There he was married to Helena , the Emperor ' s sister , and promoted to the rank of Caesar . Although Constantius felt obliged to elevate Julian , the only other male descendant of Constantine the Great still living , it was clear that none of his habitual distrust had abated . Although Julian had no military experience whatsoever , he was promptly sent with a small escort to reorganise the army in Gaul , under attack by invading German tribes . Again according to Ammianus , despite Julian ' s sudden promotion , Constantius saw him as a possible rival and despised him for his " … youthful vivacity , sincerity , and wit which made him too popular for the Emperor ' s peace of mind . " The army officers were instructed that they had the real power , not Julian . It seems likely that Constantius sent him to the dangerous frontier in Gaul , expecting him to die in battle . But Julian was to prove himself to be a skilful soldier with natural ability . In 357 , Julian ' s second year as Caesar , plans were laid for an offensive against the Alamanni , the most dangerous of the enemy tribes . It was intended that two armies , the first commanded by Julian and the second by Barbatio , would advance in a classic Roman tactic known as a " forceps " or " forfex " , forming diverging wings , embracing and destroying the enemy . Julian then marched from his camp in Sens to Reims , while Barbatio moved north with 25 , 000 troops from Italy to Raetia . While these moves were underway another German tribe , the Laeti , passed between both armies and attacked Lyons . Julian sent three elite cavalry squadrons to intercept them , attacking and killing a large number as they returned from the raid loaded with booty . The survivors fled past Barbatio ' s camp unchallenged . The commander excused himself to the Emperor by blaming others for his neglect of duty . Still later , Julian asked Barbatio for some boats to form a pontoon bridge over the Rhine to pursue another enemy tribe . Barbatio simply had the boats burned . Supplies intended for Julian ' s army were also destroyed . Eventually the planned pincer movement was frustrated when Barbatio , in the words of Ammianus , " … as if he had ended the campaign successfully , distributed his soldiers in winter quarters and returned to the Emperor ' s court to frame some charges against Caesar , as was his custom . " His departure left Julian open to attack , but against all expectations he defeated the Alemanni at the Battle of Strasbourg . Constantius , in distant Milan , immediately claimed the victory as his own . Edward Gibbon hypothesized that Barbatio , who escaped all reprimand , could have only acted as he did under instruction . Gibbon wrote in " The History of the Decline and Fall of the Roman Empire " , " But the hopes of the campaign were defeated by the incapacity , or the enemy , or the secret instructions of Barbatio ; who acted more as if he had been an enemy of the Caesar and a secret ally of the Barbarians " Treason and death . In 359 , with Barbatio away on another campaign , his wife , Assyria , whom Ammanius describes as an " indiscreet and silly woman " , decided to write to him , seemingly fearful that he was about to cast her off . Her letter , which has not survived , hinted , in Ammianus ' account , at Barbatio ' s own imperial ambitions , and his possible intention of marrying the Empress Eusebia in the event of Constantius ' death . It was not composed by Assyria herself , but by a female slave , who had formerly belonged to Silvanus , and may possibly have harboured some grudge towards her new owners . The servant immediately took a copy of this letter to Arbitio , suggesting that the whole thing was part of an elaborate plot . Arbitio at once brought the matter to the attention of Constantius . Barbatio was arrested and confessed that he had received the letter . Both he and Assyria were subsequently executed . There is no evidence at all that Barbatio actually planned to murder Constantius . According to some historians , it seems more likely that , following his usual pattern of behaviour , he simply wished to ingratiate himself still further with the Emperor , with the possible hope of becoming a co - Augustus . It is also questionable if the incriminating letter contained Assyria ' s actual words .