After the death of Julian in Persia in 363, the Alemans, forgetting the treaty of truce which the emperor had extorted from them after his four successful campaigns beyond the Rhine (in 357, 358, 359, and 360),[1] renewed their incursions into Gaul, alleging as the pretext for war the contempt of Valentinian I's ministers in failing to supply them the accustomed tribute.

The enraged emperor, after restoring by a severe sentence the discipline of the legions, entrusted the command to Jovinus, an able officer who soon proved his qualification for the appointment by the total discomfiture of the invaders.

Rando, a barbarian chieftain, in early 368 fell unexpectedly on the town of Moguntiacum (modern Mainz) on the Rhine, and put the defenceless inhabitants to the sword, before retiring over the river.

Finding their arms inadequate for the defence of their fields and villages, the Alemans retreated into the mountains, erecting their camp on an unidentified hill referred to as "Solicinium", in the area of Württemberg.

It appears that Valentinian carried their defenses by a general assault, charging up the slope, and the barbarians, when they were ejected from the summit, were driven down the opposite side of the hill into the clutches of Sebastian, who had been placed in their rear to anticipate the retreat.