The Battle of Brenta was fought between the cavalry of the Kingdom of Italy under king Berengar I and the Hungarians, hired by the East Francian king Arnulf of Carinthia, against him, at an unidentified location in northern Italian Peninsula along the river Brenta on 24 September 899.
It was one of the earliest battles of the Hungarian invasions of Europe. The result was a crushing defeat for Berengar I, opening the following raids for the Hungarians against Italy. The Hungarian invasion resulted in the burning of many cities, like Feltre, Vercelli, Modena and monasteries like the monastery in Nonantola, and attacking even Venice, however without success.
In the meantime Berengar's arch enemy, Arnulf of Carinthia died in December 899, as a result the Hungarians, whom he hired against the Italian king, left the kingdom in the next year with all their plunders, not before concluding peace with Berengar, who gave them many hostages and "gifts". On their way home the Hungarians made an "amphibious assault", a unique achievement from an exclusively land army in the pre-modern times, crossing the Adriatic Sea in order to attack Venice.
In some historians' opinion the returning army had a role also in the conquering of Pannonia, as part of the Hungarian conquest of the Carpathian Basin, from the Bavarians by the Hungarians in late 900.
Ironicaly, the Hungarian king Béla IV shared Berengars fate when a westernized Kingdom of Hungary faced the Mongol invasion in the battle of Muhi, 1241.