The battle of Suthul (late 110 BC or early 109 BC) was a Roman defeat early in the Jugurthine War and saw Aulus Postumious Albinus forced to surrender on harsh terms after his army was forced out of its camp in a night attack.
The consul Spurius Postumius Albinus had been given the Numidian command for 110 BC, possibly after helping to undermine an earlier peace deal. However he didn’t achieve much during his time in Africa, as Jugurtha refused to fight on Roman terms. Eventually the consul had to return to Rome to conduct the elections for 109 BC, but he was then trapped in Rome by an ongoing dispute over the re-election of two of the tribunes of the plebs. He left his brother, Aulus Postumius Albinus, in command of the army.
Aulus eventually decided to go onto the offensive. According to Sallust he broke camp in January 109 BC, and advanced towards the town of Suthul, where Jugurtha had his treasury. Sallust describes Suthul as having walls build on the edge of a steep hill (although it isn't clear if they were at the top or the bottom of the hill), and being protected by a marshy valley that had been flooded by winter rains and become a lake. The location of Suthul is unknown, and there are plenty of sites in the mountains of north-eastern Algeria that could fit this description.
Orosius places this battle at Calama. He gives Aulus Postumius Albinus 40,000 men, and also places the Numidian treasury in the city. After the defeat Aulus was forced to agree to a humiliating treaty. The location of Calama is known - it was at the site of modern Guelma, in north-eastern Algeria, located on the south bank of the Seybouse River (the ancient Ubus) in mountainous terrain. While the Seybouse valley could match the marshy plain described in Sallust, the Roman theatre and thus perhaps the Numidian city at Calama are in the valley. Calama could be the location of Suthul, but there is really no proof either way.
In either case the battle was probably fought somewhere in this part of eastern Numidia, as there is nothing in our sources to suggest that either Albinus reached as far as the capital at Cirta, another fifty miles to the west.
After arriving outside Suthul, Albus prepared for a regular siege, building a rampart outside the city. Jugurtha's army was clearly close by, and he finally decided to risk an attack on the Romans. Even now he wasn't willing to risk a direct attack, but instead decided to try and draw Albus into an ambush while undermining the morale of his army. He sent envoys into the Roman camp to try and convince some of the Romans or their allies to desert at a set time. He also sent messengers to Albus hinting that he might be willing to surrender. He then led his army away from Suthul along minor roads as if he was trying to escape.
Albus fell into the trap. He lifted the siege, and followed Jugurtha into increasingly remote parts of Numidia. Once the Romans were dangerously isolated, Jugurtha strung his trap. One dark and stormy night he surrounded the Roman camp with a vast army, and gave the signal for the deserters to make their move. One cohort of Ligurians and two troops of Thracian cavalry deserted, but the most serious blow came from the chief centurion of the Third Legion, who opened the gate he was guarding and allowed the Numidians into the camp. The Roman army collapsed into chaos and the survivors fled to a nearby hill. Jugurtha's men were distracted by the amount of loot in the camp, and failed to take full advantage of the chaos.
On the following morning Jugurtha offered Albus surrender terms - the Romans would have to pass under the yoke and leave Numidia within ten days. Faced with the choice between these harsh terms or the destruction of his army, Albus accepted the terms.
Unsurprisingly the news of this surrender caused great consternation at Rome. Aulus was condemned for his actions. His brother Spurius raised fresh troops, and then returned to Africa, intended to go onto the offensive to try and restore the family name, but found that the army was in terrible shape and had to abandon his plans.
Although the battle of Suthul was a clear victory for Jugurtha, it changed the nature of the war. Until then, Jugurtha had carefully avoiding a direct clash with the main Roman army, in the hope that he could eventually make peace with the Romans on reasonable terms. After suffering humiliation at Suthul, the Romans were unlikely to make peace on any terms that would have left Jugurtha in power.