The Numidians, led by their king Jugurtha, fought a Roman army commanded by the consul Quintus Caecilius Metellus Numidicus.
[1] It has been identified as the Wäd Mellag,[2] and in this case Metellus would have started his campaign in south-east Numidia, with the aim of strengthening his communication links.
Other views (Mannert and Forbiger) identify the Muthul with the river Ubus, with Metellus starting his campaign in western Numidia, and later returning to Zama.
His army had to descend from the mountains and cross a desert plain eighteen miles wide to reach the Muthul River where he could refill his water reserves.
Descending from the mountain pass, Metellus noticed the ambush, but his army needed to refill its water reserves, and thus had to cross the desert without cavalry coverage and within sight of the enemy.
At this point Gaius Marius, an officer who had risen from the ranks, re-organized a few detachments, and led a column of 2,000 soldiers through the Numidians to free his commander Metellus.
From this position, Marius led his men against the rear of the Numidian cavalry, uniting the separated Roman detachments into a single army.