The armies face off: Romans at right, Ambrones at left. Close-up of each below.
Marius decided to mass the skirmishers from both commands in front of the legionaries from his command, to combine the Roman and Italian cavalry on the right flank, using part of the rear line of legionaries (from Catalus' command) to protect the left flank.
The Ambrones surged forward, the left-most cavalry getting the better of the Romans
Not surprisingly as the partially-trained Roman legionaries began to melt away from the warbands.
The Italian cavalry were fairing a little better than the Romans, but only just...
while Catalus' legionaries saw off the barbarian cavalry attempting to come around the Roman left flank.
Gaius Marius, where are my "rock-hard" Roman legions?!