page_title: Campaign history of the Roman military
section_title: Imperial expansion (40 BC – 117 AD)
hierarchical_section_title: Campaign history of the Roman military / Empire / Early to Middle (30 BC – 180 AD) / Imperial expansion (40 BC – 117 AD)
context_page_description: From its origin as a city-state on the peninsula of Italy in the 8th century BC, to its rise as an empire covering much of Southern Europe, Western Europe, Near East and North Africa to its fall in the 5th century AD, the political history of Ancient Rome was closely entwined with its military history. The core of the campaign history of the Roman military is an aggregate of different accounts of the Roman military's land battles, from its initial defense against and subsequent conquest of the city's hilltop neighbors on the Italian peninsula, to the ultimate struggle of the Western Roman Empire for its existence against invading Huns, Vandals and Germanic tribes. These accounts were written by various authors throughout and after the history of the Empire. Following the First Punic War, naval battles were less significant than land battles to the military history of Rome due to its encompassment of lands of the periphery and its unchallenged dominance of the Mediterranean Sea.
  The Roman army battled first against its tribal neighbours and Etruscan towns within Italy, and later came to dominate the Mediterranean and at its height the provinces of Britannia and Asia Minor.
context_section_description: Secured from internal threats, Rome achieved great territorial gains in both the East and the West. In the West, following humiliating defeats at the hands of the Sugambri, Tencteri and Usipetes tribes in 16 BC, Roman armies pushed north and east out of Gaul to subdue much of Germania. The Pannonian revolt in 6 AD forced the Romans to cancel their plan to cement their conquest of Germania. Despite the loss of a large army almost to the man of Varus' famous defeat at the hands of the Germanic leader Arminius in the Battle of the Teutoburg Forest in 9 AD, Rome recovered and continued its expansion up to and beyond the borders of the known world. Roman armies under Germanicus pursued several more campaigns against the Germanic tribes of the Marcomanni, Hermunduri, Chatti, Cherusci, Bructeri, and Marsi. Overcoming several mutinies in the armies along the Rhine, Germanicus defeated the Germanic tribes of Arminius in a series of battles culminating in  the Battle of the Weser River.
  After Caesar's preliminary low-scale invasions of Britain, the Romans invaded in force in 43 AD, forcing their way inland through several battles against British tribes, including the Battle of the Medway, the Battle of the Thames, the Battle of Caer Caradoc and the Battle of Mona. Following a general uprising in which the Britons sacked Colchester, St Albans and London, the Romans suppressed the rebellion in the Battle of Watling Street and went on to push as far north as central Scotland in the Battle of Mons Graupius. Tribes in modern-day Scotland and Northern England repeatedly rebelled against Roman rule and two military bases were established in Britannia to protect against rebellion and incursions from the north, from which Roman troops built and manned Hadrian's Wall.
  On the continent, the extension of the Empire's borders beyond the Rhine hung in the balance for some time, with the emperor Caligula apparently poised to invade Germania in 39 AD, and Cnaeus Domitius Corbulo crossing the Rhine in 47 AD and marching into the territory of the Frisii and Chauci. Caligula's successor, Claudius, ordered the suspension of further attacks across the Rhine, setting what was to become the permanent limit of the Empire's expansion in this direction.
  Further east, Trajan turned his attention to Dacia, an area north of Macedon and Greece and east of the Danube that had been on the Roman agenda since before the days of Caesar when they had beaten a Roman army at the Battle of Histria. In 85 AD, the Dacians had swarmed over the Danube and pillaged Moesia and initially defeated an army the Emperor Domitian sent against them, but the Romans were victorious in the Battle of Tapae in AD 88 and a truce was drawn up.
  Emperor Trajan recommenced hostilities against Dacia and, following an uncertain number of battles, defeated the Dacian general Decebalus in the Second Battle of Tapae in 101 AD. With Trajan's troops pressing towards the Dacian capital Sarmizegethusa, Decebalus once more sought terms. Decebalus rebuilt his power over the following years and attacked Roman garrisons again in 105 AD. In response Trajan again marched into Dacia, besieging the Dacian capital in the Siege of Sarmizethusa, and razing it to the ground. With Dacia quelled, Trajan subsequently invaded the Parthian empire to the east, his conquests taking the Roman Empire to its greatest extent. Rome's borders in the east were indirectly governed through a system of client states for some time, leading to less direct campaigning than in the west in this period.
  The Kingdom of Armenia between the Black Sea and Caspian Sea became a focus of contention between Rome and the Parthian Empire, and control of the region was repeatedly gained and lost. The Parthians forced Armenia into submission from 37 AD but in 47 AD the Romans retook control of the kingdom and offered it client kingdom status. Under Nero, the Romans fought a campaign between 55 and 63 AD against the Parthian Empire, which had again invaded Armenia. After gaining Armenia once more in 60 AD and subsequently losing it again in 62 AD,
caption: The Roman Empire at its greatest extent under Trajan in 117 AD