The battle of Noreia (113 BC) was the first battle of the Cimbric War, and saw a migrating Cimbric army defeat the Roman consul Papirius Carbo after he attempted to ambush them as they were withdrawing from Noricum.
The Cimbri were probably a Celtic or Germanic tribe from the Jutland area, forced into a large scale migration by rising sea levels. By 113 BC their wanderings brought them towards Noricum, on the north-eastern corner of the Alps. The Taurisci, newly acquired Roman allies in that area, sent a message to the senate reporting the migration and asking for help. The Romans sent the consul Cn. Papirius Carbo to investigate the new threat and deal with it as he saw fit.
We don't have any detailed accounts of the battle, but several short mentions and one brief narrative.
The Periochae of Livy tells us that Papirius Carbo was defeated by the Cimbri in Illyricum.
Strabo mentioned that 'Gnaeus Carbo clashed to no effect with the Cimbri' near the city of Noreia, giving the battle its name. This placed the battle at modern Neumarkt, in Styria in south-central Austria.
The longest account comes from a fragment from Appian's Gallic History. He makes the invaders the Teutones, who have invaded the territory of Noricum searching for plunder. Carbo took up a position in a pass across the Alps to protect against any invasion of Italy. When the Teutones didn't come that way, Carbo led his army north to attack them, on the grounds that they had attacked a Friend of the Roman Republic. The Teutones sent ambassadors to Carbo who stated they hadn't known about the relationship between Rome and Noricum, and promised to withdraw and not attack them again. Carbo pretended to accept this apology, and sent guides to help the Teutones at the start of their journey home, but his real plan was to ambush them. The guides led the Teutones along a long route, while the Romans took a shortcut. The plan ended as a costly failure - the Teutones defeated Romans, and only darkness and a thunder-storm saved Carbo's army from total destruction. The surviving Romans scattered into small bands and escaped through some nearby woods. Carbo was amongst the survivors, although his reputation was destroyed. In the aftermath of this victory the Teutones decided to move west or north-west into Gaul, instead of risking an invasion of Italy.
Appian's account presents us with a number of problems, starting with the identity of Rome's opponents. Although he says they were the Teutones, this doesn't agree with Livy or Strabo, and it is more likely that the Cimbri were the real foe at Noreia. The second is how Carbo was defeated when he was launching an ambush. The answer here is that he probably didn't know how large the Cimbric army actually was, and ended up being massively outnumbered when he ran into the main body of the migrating tribe.
We know frustratingly little about this battle, including the size of either army, the losses on either side, or the actual course of the battle.
After this victory, the Cimbri disappear from the Roman sources until 109 or 108 BC, when they reappeared on Rome's north-western border, probably in Gaul. Once again they were able to defeat a Roman army, this time under the consul M. Iunis Silanus, at an unknown location. This time we know even less about the battle, with at least one source even making it a Roman victory!