The north of Italy was also threatened by the rude people beyond the Alps, from the borders of Gallia to the eastern side of the Hadriatic.  These barbarians attempted to break into Italy, as the Germanic nations had attempted near three hundred years before; and the rest of the life of Antoninus, with some intervals, was employed in driving back the invaders.  In 169 Verus suddenly died, and Antoninus administered the state alone.

During the German wars Antoninus resided for three years on the Danube at Carnuntum.  The Marcomanni were driven out of Pannonia and almost destroyed in their retreat across the Danube; and in A.D. 174 the emperor gained a great victory over the Quadi.

In A.D. 175, Avidius Cassius, a brave and skilful Roman commander who was at the head of the troops in Asia, revolted, and declared himself Augustus.  But Cassius was assassinated by some of his officers, and so the rebellion came to an end.  Antoninus showed his humanity by his treatment of the family and the partisans of Cassius; and his letter to the Senate, in which he recommends mercy, is extant. (Vulcatius, Avidius Cassius, c. 12.)

Antoninus set out for the East on hearing of Cassius’ revolt.  Though he appears to have returned to Rome in A.D. 174, he went back to prosecute the war against the Germans, and it is probable that he marched direct to the East from the German war.  His wife Faustina, who accompanied him into Asia, died suddenly at the foot of the Taurus, to the great grief of her husband.  Capitolinus, who has written the life of Antoninus, and also Dion Cassius, accuses the empress of scandalous infidelity to her husband, and of abominable lewdness.  But Capitolinus says that Antoninus either knew it not or pretended not to know it.  Nothing is so common as such malicious reports in all ages, and the history of imperial Rome is full of them.  Antoninus loved his wife, and he says that she was “obedient, affectionate, and simple.”  The same scandal had been spread about Faustina’s mother, the wife of Antoninus Pius, and yet he too was perfectly satisfied with his wife.  Antoninus Pius says after her death, in a letter to Fronto, that he would rather have lived in exile with his wife than in his palace at Rome without her.  There are not many men who would give their wives a better character than these two emperors.  Capitolinus wrote in the time of Diocletian.  He may have intended to tell the truth, but he is a poor, feeble biographer.  Dion Cassius, the most malignant of historians, always reports, and perhaps he believed, any scandal against anybody.

Antoninus continued his journey to Syria and Egypt, and on his return to Italy through Athens he was initiated into the Eleusinian mysteries.  It was the practice of the emperor to conform to the established rites of the age, and to perform religious ceremonies with due solemnity.  We cannot conclude from this that he was a superstitious man, though we might perhaps do so if his book did not show that he was not.  But that is only one among many instances that a ruler’s public acts do not always prove his real opinions.  A prudent governor will not roughly oppose even the superstitions of his people; and though he may wish they were wiser, he will know that he cannot make them so by offending their prejudices.