The Battle of Placentia was fought in January 271 between a Roman

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

 army led by Emperor Aurelian

Aurelian

Aurelian , was Roman Emperor from 270 to 275. During his reign, he defeated the Alamanni after a devastating war. He also defeated the Goths, Vandals, Juthungi, Sarmatians, and Carpi. Aurelian restored the Empire's eastern provinces after his conquest of the Palmyrene Empire in 273. The following...

 and the Alamanni

Alamanni

The Alamanni, Allemanni, or Alemanni were originally an alliance of Germanic tribes located around the upper Rhine river . One of the earliest references to them is the cognomen Alamannicus assumed by Roman Emperor Caracalla, who ruled the Roman Empire from 211 to 217 and claimed thereby to be...

 (actually the Juthungi

Juthungi

The Juthungi were a Germanic tribe in the region north of the rivers Danube and Altmühl in the modern German state of Bavaria....

 tribe), near modern Piacenza

Piacenza

Piacenza is a city and comune in the Emilia-Romagna region of northern Italy. It is the capital of the province of Piacenza...

.

The Alamanni had invaded Italia

Italia (Roman province)

Italia was the name of the Italian peninsula of the Roman Empire.-Under the Republic and Augustan organization:During the Republic and the first centuries of the empire, Italia was not a province, but rather the territory of the city of Rome, thus having a special status: for example, military...

, counting on the absence of the Roman Army

Roman army

The Roman army is the generic term for the terrestrial armed forces deployed by the kingdom of Rome , the Roman Republic , the Roman Empire and its successor, the Byzantine empire...

, and sacked the city of Placentia. Emperor Aurelian, who was in Pannonia

Pannonia

Pannonia was an ancient province of the Roman Empire bounded north and east by the Danube, coterminous westward with Noricum and upper Italy, and southward with Dalmatia and upper Moesia....

 with an army to control the withdrawal of the Vandals

Vandals

The Vandals were an East Germanic tribe that entered the late Roman Empire during the 5th century. The Vandals under king Genseric entered Africa in 429 and by 439 established a kingdom which included the Roman Africa province, besides the islands of Sicily, Corsica, Sardinia and the Balearics....

, quickly moved into Italia. The Alamanni surprised the Roman Army with an ambush, and the Emperor was defeated.

The news of this defeat produced great fear in Rome, and the Alamanni continued to move towards the capital, which had grown far beyond its old walls. The Sibylline Books

Sibylline Books

The Sibylline Books or Libri Sibyllini were a collection of oracular utterances, set out in Greek hexameters, purchased from a sibyl by the last king of Rome, Tarquinius Superbus, and consulted at momentous crises through the history of the Republic and the Empire...

 were consulted, and religious ceremonies performed to call for the gods' help. The Romans escaped disaster when Emperor Aurelian soundly defeated the Alamanni at the Battle of Fano

Battle of Fano

The Battle of Fano - also known as the Battle of Fanum Fortunae - was fought in January 271 between the Roman Empire and the Alamanni. The Romans were led by Emperor Aurelian, and they were victorious....

, leading to great celebration throughout the city.