Battle of the Tolenus River

The Battle of the Tolenus River was fought on 11 June 90 BC between the Roman Republic, led by the consul Publius Rutilius Lupus, and an army of Marsian Rebels commanded by Titus Vettius Scato. The battle was part of the Social War and resulted in a major defeat for the Romans.

Background
Publius Rutilius Lupus and Lucius Julius Caesar were elected as consuls for the year 90 BC and dispatched to command armies in the Social War, which had begun during the prior year with the rebellion of Asculum. While Lucius Caesar marched against the Samnites, Rutilius was sent to face the Marsi, selecting Gaius Marius as his senior legate.

Battle
Rutilius and Marius constructed two bridges across the Tolenus River in eastern Latium, pitching camps on one side of the river, while the Marsian commander Titus Vettius Scato set up camp on the other side of the river, nearer to Marius's camp. The night before the battle, Scato sent an ambush force to the location of Rutilius's bridge, and when Rutilius attempted to cross with his army in the morning, they were attacked, and Rutilius was killed.

Marius, downstream from the attack, observed bodies floating down the river and therefore decided to advance across the river, taking Scato's undermanned camp by surprise and forcing Scato to retreat with his ambush force in search of provisions.

Aftermath
The Battle of the Tolenus River was the largest engagement of the Social War thus far, with around 8,000 killed on both sides. Despite the equal losses, the battle was unquestionably a Roman defeat with the death of the consul Rutilius. The senate decided against holding elections to replace Rutilius, instead handing control of his army jointly to Marius and Quintus Servilius Caepio.