The Battle of Pollentia was fought on 6 April 402 (Easter) between the Romans and the Visigoths.
Theodosius I, the last emperor of both eastern and western halves of the Roman Empire, died in 395, leaving his sons Arcadius and Honorius emperors of the East and West, respectively. Both new emperors were only boys at their ascension to the thrones, thereby making it necessary for older and more experienced men to step in as consuls.
Flavius Stilicho, son of a Vandal father, though he identified with his maternal Roman heritage, was the magister utriusque militae when Honorius came to power and was able to act as consul and commander-in-chief because of his close relationship to the imperial family. Theodosius I had great trust in Stilicho and their families became formally linked when Stilicho’s daughter was married to Honorius. Zosimus described the concurrent situation: "The empire now devolved upon Arcadius and Honorius, who, although apparently the rulers, were so in name only: complete control was exercised by Rufinus in the east and Stilicho in the west." Even as Honorius grew older (he was ten at his ascension and seventeen at the Battle of Pollentia) “[he] was a feeble nonentity.”:430
Meanwhile, the disgruntled Visigoths ended their service to the empire as foederati on the charge that they were not being compensated as promised. They began wreaking havoc in land very close to Constantinople and ironically, the city had to buy off the Visigoths to end the threat. This short-sighted policy of bribery proved ineffective and Alaric, king of the Visigoths, devastated the Peloponnese and Balkans in the following year.:17 After he had good control over the Balkan region, Alaric then tried negotiating with the western empire for senior military rank (magister militum) and rations of food and supplies for his troops. He was rebuffed – Roman government thought it was beneath them to make deals with barbarians.:294
Alaric set his sights on Gaul (historians are not sure why he chose this region) and began marching, invading Italy in early 402 on his way across the western empire. General Stilicho was concurrently occupied at Raetia (modern Austria) and Noricum in the north dealing with Vandal and Alan raids. When he heard of Alaric’s invasion, Stilicho quickly recruited troops from the very people he was fighting in order to gain enough manpower to confront the Visigoths.:120
Since February, the Visigoths, led by Alaric, had besieged the Emperor Honorius of the Western Roman Empire in the fortress of Hasta in Liguria. Hasta (modern Asti) had become the refuge for the beleaguered emperor after the Visigoths had advanced rapidly through northern Italy during the autumn of 401. The Visigoths had been assisted by the unseasonably dry weather in northern Italy and also by the absence of most of the imperial troops that would normally have been stationed in Italy. These circumstances had left Mediolanum, the imperial capital, and the young emperor within, both dangerously exposed.
As the enemy approached the city outskirts in early 402, Honorius and his retainers decided to flee and attempt to relocate the imperial court to Arles in Gaul. However, after he had vacated the city, his alpine escape route was cut off by the Visigoth cavalry. With the option to retreat back to Mediolanum now lost (by now the Visigothic infantry had the city surrounded), the desperate convoy of Honorius headed south to the fortified city of Asta or Hasta, pursued by the Visigoths. As soon as the emperor arrived, the Visigoths immediately placed the city under siege, hoping to capture him as a valuable hostage.
General Stilicho crossed the Po and reached the Visigoth army besieging Hasta. The Visigoths retreated to Pollentia (modern Pollenzo). On Easter Sunday, 6 April 402, the Visigoths, who were Arian Christians, were distracted and celebrating the holiday when Stilicho decided to time a strategic attack.:55 The result was a very costly draw. Although there was no clear victor, Stilicho had managed to capture Alaric's wife, children, and other important relations. Serena, wife of Stilicho, paid for a musive floor in the basilica of the Apostles in Mediolanum as an ex-voto for Stilicho's victory. And despite the Battle of Pollentia not being a decisive victory for Stilicho, the poet Claudian still praises it: "Thy glory, Pollentia, shall live for ever...Fate pre-ordained thee to be the scene of our victory and the burial-place of the barbarians."
Stilicho offered to return the prisoners in exchange for the Visigoths returning to Illyricum, but upon reaching Verona, Alaric stopped his retreat and endeavoured to capture the city.:431 Stilicho and local forces surrounded the Visigoths and defeated them in the Battle of Verona. With many of his generals deserting him and swearing allegiance to Stilicho, Alaric was forced to leave Italy.
By 403 Alaric and the Visigoths had been pushed back to the Balkans where they remained a minor threat.:512 In 405 (according to Adrian Goldsworthy) or 407 (according to Averil Cameron) Stilicho and Alaric formed a treaty which conceded the latter's demands of title for himself and concession of 4,000 pounds of gold for his troops in exchange for absolute allegiance to the former.:139 Many senators were already upset that Stilicho wielded so much power and influence over the emperor Honorius and they knew he had his sights on the eastern empire as well. When the senators heard of this treaty with the barbarian king Alaric it was the straw that broke the camel's back. General Stilicho was declared a public enemy and guilty of treason in 408. He was executed shortly after.:139
Modern historian Peter Brown believes this was a big mistake. "A strident chauvinism and a refusal to negotiate with the barbarians led to the sack of Rome in 410", during which Romans had to pay three times as much as Alaric originally wanted in order to ransom their city back from the Visigoths.:124