Roman Britain’s Lost Ninth Legion

Simon Elliott

The ancient historian considers the evidence for the theories which aim to provide an explanation for the mysterious disappearance of the Ninth.
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Roman Britain’s Lost Ninth Legion

The fate of the 5,500 men of legio IX Hispana is one of the greatest historical mysteries of all time. Uniquely among the Roman legions, of which there were over time more than 60 (and at any one time in the Empire a maximum of 33), we have no idea what happened to it. It simply disappears from history, and is a tale which I have loved researching for my recent book through Pen & Sword,‘Roman Britain’s Missing: What Really Happened to legio IX Hispana.’ 

This historical conundrum has grabbed the attention of academics, scholars and the wider public for hundreds of years. One of the first to write on the subject was British antiquarian John Horsley who published his Britannia Romana: The Roman Antiquities of Britain in 1732. In this work he detailed when each Roman legion arrived and left Britain. However, he noted that there was no leaving date for legio IX Hispana, a fact he found difficult to explain. Then, in the 1850s, the renowned German scholar Theodor Mommsen published his multi-volume History of Rome. In this he speculated that the IXth legion had been the subject of an uprising by the Brigantes tribe of northern Britain around AD 117/ 118, it being wiped out in its legionary fortress at York (Roman Eboracum). Mommsen speculated it was this event that prompted the new Emperor Hadrian to later visit Britain in AD 122 and initiate the construction of Hadrian’s Wall.

Such was Mommsen’s reputation that his theory became the received wisdom regarding the legion’s fate well into the 20th century AD, when it was then popularized by a number of historical fiction works. One above all others cemented the fate of legio IX Hispana in the popular imagination. This was The Eagle of the Ninth, the seminal work published by children’s author Rosemary Sutcliffe in 1954. Her second book, this told the story of her hero Marcus Flavius Aquila who travelled north of Hadrian’s Wall to track down the fate of his father’s legion, legio IX Hispana. Her conceit was that the IXth legion had been annihilated in the far north of Britain, beyond the northern border rather than in York, during yet another uprising. This novel proved as popular with adults as with children, capturing the imagination of an entire generation, and is still a bestseller to this day. The story of the IXth legion also became the subject of an eponymous BBC TV series in 1977, and later received the attentions of Hollywood with blockbusters such as 2010’s The Centurion and 2011’s The Eagle.

Given this level of popular interest in the fate of the IXth legion, it is often difficult to separate fact from fiction. However, there are a number of incontestable hard facts known about the IXth legion, which enable us to speculate in an informed way regarding its fate. These are:

  • 90/ 89 BC. The original IXth legion participated in the year long Siege of Asculum in the Social War in Italy when Gnaeus Pompeius Strabo led his Roman army to victory over their former Italian allies.
  • 58 BC – 45 BC. This earlier IXth legion participated in Julius Caesar’s Gallic conquests, including his two British incursions in 55 and 54 BC, and later in the civil wars when Caesar’s populares supporters fought Pompey’s optimates supporters in Greece, Egypt, Africa and Spain. It was then disbanded in 45 BC, for unknown reasons.
  • 44/ 43 BC. The actual IXth legion that is the subject of popular interest was raised by Octavian shortly afterwards, from Caesarean veterans settled in Italy to counter the rebellion of Sextus Pompeius in Sicily.
  • 42 BC. The new legion participated at the Battle of Philippi when Octavian and Mark Antony defeat the Caesarean assassins Gaius Cassius Longinus and Marcus Junius Brutus. It performed well and is shortly afterwards awarded a cognomen styling it legio IX Macedonia.
  • 27 BC – 19 BC. The IXth legion participated in Augustus’ Cantabrian Wars, the final stage of the Roman conquest of the Iberian Peninsula. The legion again fought with great bravery, afterwards staying in Spain long enough for its cognomen to change from Macedonia to Hispaniensis. This is later shortened to Hispana.
  • 10 BC. The IXth legion was redeployed to Aquileia in northeastern Italy.
  • AD 14. The IXth legion was redeployed once more, to a legionary fortress in Pannonia on the Danube. It was one of three legions which mutinies over the living conditions there given it is forced to share the fortress with two other legions.
  • AD 20. The IXth legion was sent to North Africa to support legio III Augusta in its campaigns against the Numidian rebel leader Tacfarinas. It participated in a major victory in AD 22.
  • AD 22. The IXth legion moved to the legionary fortress at Sisak in modern Croatia, later returning to Pannonia.
  • AD 43. Aulus Plautius led the Claudian invasion of Britain, with four legions including his own legio IX Hispana (the latter from the province of Pannonia where he had been governor). The legion played a full role in the early campaigns of conquest, which led to the establishment of the original province of Britannia.
  • AD 44 – AD 49. The IXth legion headed north as part of the initial breakout campaigns in Britain, skirting the territory of the Iceni tribe in modern Norfolk (a Roman client kingdom), then reaching the River Nene where it established a vexillation fort at Longthorpe. It continued north to found another vexillation fort at Leicester, and then a full legionary fortress at Lincoln on the River Witham.
  • AD 60 – 61. A significant component of legio IX Hispana under its legate Quintus Petillius Cerialis was defeated trying to prevent the sack of Colchester during the Boudiccan Revolt. Some surviving vexillations of legionaries may have joined the governor Gaius Suetonius Paulinus in the Midlands where he ultimately defeated Boudicca.
  • AD 71. Cerialis returned to Britain as governor and targeted the Brigantes tribe in the north. He ordered legio IX Hispana from Lincoln into Yorkshire where it constructed a new legionary fortress at York on an easily defendable plateau at the confluence of the Rivers Ouse and Foss, deep in Brigantian territory.
  • AD 82. The legion is last mentioned in contemporary history in AD 82 by Tacitus in the context of Agricola’s campaigns to conquer the far north of Britain, when the IXth’s marching camp is almost overrun by native Britons. Tacitus says Agricola had to come to its rescue.
  • AD 83. The IXth legion was present at the Battle of Mons Graupius in the far north of Scotland, though took no part given the fighting is carried out by the Roman auxiliaries.
  • At some stage between AD 104 – AD 120. A vexillation of legionaries from the IXth legion was redeployed to the legionary fortress of Nijmegen in Germania Inferior. This forms part of a composite force from Britain’s three legions to replace legio X Gemina that had redeployed to the Danube frontier to participate in Trajan’s Dacian campaigns.
  • AD 108. It is last recorded in epigraphy on an inscription referencing the IXth legion in Britain, this found on an inscribed limestone slab that formed the centre section of a monumental inscription referencing the rebuilding of the southeastern gate at the legionary fortress in York.
  • AD 122. Arrival in Britain of legio VI Victrix in York to replace legio IX Hispana.
  • AD 120s. Hadrian’s Wall is built, with no inscriptions suggesting legio IX Hispana
  • Around AD 168. Construction of the Collonetta Maffei pillar in Rome with its nomina legionum list of contemporary extant legions. The IXth legion is missing, and never mentioned again.


Of these hard facts, five are the most important regarding the fate of the IXth legion, namely that it is last mentioned in literature in AD 82, in inscription in Britain in AD 108, it was replaced in York by legio VI Victrix in AD 122, there are no inscriptions referencing it on Hadrian’s Wall, and it is missing from the Collonetta Maffei pillar list of legions in Rome from AD 168. The legionary tile and brick stamps from Nijmegen are also important, but the dating of between AD 104 and AD 120 isn’t tight enough to be especially useful.

Based on the above detail, in my recent book I was able to tighten the various theories regarding the fate of the IXth legion down to four broad hypotheses. These are that it was 1). lost or disbanded in the north of Britain, that it was 2). lost or disbanded in an insurrection in the south of Britain, that it was 3). lost or disbanded on the Rhine or Danube, or that it was 4). lost or disbanded in the east.

Taking these in turn, most commentators still favour the legion being ‘lost in the north’ as I style it. A number of scenarios are possible here, principally that the legion was the subject of a devastating local insurrection in the province as speculated by Mommsen, that it was lost campaigning north of the frontier in the region of modern Scotland as speculated by Sutcliffe, or that a combination of both led to a region wide conflagration akin to Boudicca’s AD 60/ 61 revolt further south.

In terms of ‘lost in the south’, here a recent theory known as the Hadrianic War in London might provide context. This is based on research by the UCL Institute of Archaeology’s Dr Dominic Perring who argued that three different events which occurred in London during the reign of Hadrian could be interpreted as evidence for what he termed a ‘Hadrianic War’ in the provincial capital, this again on the scale of the Boudiccan Revolt. The events he considered were:

  • The finding of large numbers of human crania within the town boundaries in the upper courses and tributaries of the Walbrook valley (this an important stream in Roman London which bisected the city).
  • The well-known Hadrianic fire in London.
  • The building of the vexillation-sized fort at Cripplegate.


In my own research I considered whether this event might provide the setting for the loss of the IXth legion, with two scenarios being examined. The first was that the insurrection in London, in this case timed around the accession of Hadrian in AD 117, was actually caused by the legion rising in revolt and then being defeated as the insurrection was stamped out. In the second, the legion was sent to London to actually put down a rebellion there, it then again being wiped out. In both scenarios, the heads in the Walbrook would then be those of beheaded IXth legion soldiers.

For the third hypothesis considering the Rhine and the Danube, I examined the opportunities the IXth legion might have had to campaign there in the 2nd century AD, having determined (based on my research) that the Nijmegen tile was actually from a single vexillation. The only major opportunity here for it to engage in major conflict was in the Marcomannic Wars of the co-emperors Marcus Aurelius and Lucius Verus, and later Commodus. Finally, in terms of the legion being lost in the east, I considered whether Trajan’s eastern campaign, the associated second Jewish ‘Kitos War’ Revolt, the Third ‘bar Kokhba’ Jewish Revolt or the AD 161-165 Roman-Parthian War might provide reasonable scenarios.

Based on the hard facts set out above, and my wider knowledge of the Roman world and military, of these four candidate hypotheses regarding the fate of legio IX Hispana, the least likely is that it was lost fighting on the Rhine or Danube. There is simply no evidence that anything other than a very specific vexillation spent some time in Nijmegen, and then the evidence trail goes cold. The next least likely hypothesis to my mind is that the legion was lost in the east. Moving on, Perring’s Hadrianic War in London has to be considered a serious candidate event in which the IXth legion met its fate, perhaps with a damnatio memoriae then wiping it from the official record. However, given the plentiful analogous and anecdotal evidence, I actually think the most likely hypothesis regarding the loss of legio IX Hispana is with it being lost in some dramatic event in the north of Britain, either within the province as the victim of a Brigantian revolt, or even further north in unconquered modern Scotland with the native tribes there the protagonists, or with the legion on the receiving end of a region-wide rebellion across the whole far north of the province and beyond.

The reality of course is that unless some fantastical new piece of evidence emerges in some long-lost contemporary history, or through the discovery of one of the archaeological finds of the century, we will never actually know the fate of the IXth legion. Until then, based on what we do know, the above is where the available evidence ultimately points: the legion was lost in the north of Britain.


Simon Elliott is an archaeologist, historian and broadcaster. He has written numerous books on the classical world, with a particular specialization in ancient warfare, and the author of Roman Britain’s Missing Legion: What Really Happened to IX Hispana published by Pen and Sword Books.

Roman Britain’s Lost Ninth Legion