"Whilst Valentinian amused himself, in the field of Mars, with the spectacle of some military sports, they suddenly rushed upon him with drawn weapons ... and stabbed the emperor to the heart, without the least opposition from his numerous train, who seemed to rejoice in the tyrant's death." ("Edward Gibbon, "The History of the Decline and Fall of the Roman Empire")
16 March 455 CE: Today, 1.558 years ago, Flavius Placidius Valentinianus Augustus, Emperor Valentinian III was murdered by two Hunnish mercenaries, probably in the pay of the wealthy and influential senator Petronius Maximus, whose wife was raped by the emperor the year before - while the Huns, Optilia and Thraustila, took revenge for the murder of their old commander, magister militum Flavius Aetius, ordered by Valentinian in 453.
Emperor of the Western Empire since the age of five, Valentian's 30 years' reign is one of the longest in Roman history, the first half of the 5th century during Valentian's rule is marked by the almost complete disintegration of Roman authority in the West under the onslaught of whole peoples on the move during the Völkerwanderung, the Migration Period, the Vandals, Franks, Visigoths and finally the Huns.
Even though his "Master of Soldiers" Aetius tried to stem the tide with what he still had available and a cunning alliance policy with the various Germanic and Steppe people and finally managed to beat Atilla, the greates threat of them all, on the Catalaunian Plains in Gaul in 451, neither the military dictatorship Rome had become nor the personal example of Valentian III, sybaritic, scheming and fickle as he was, were the proper preconditions to turn the tables. Twenty years and ten emperors after Valentinan's death, the Western Roman Empire finally perished in 476.
The picture to the left above is probably a contemporary bust of Valentian III while the image to the right is my first personal acquaintance with the late-Roman emperor: Hal Foster's "Prince Valiant" witnessing the assassination of the emperor (first published in the Sunday New Orleans Times Picayune in 1939).