What actually happened to the Roman Ninth Legion that "vanished" from present day Scotland in the second century?

The theory that the ninth marched into history in Scotland was a great tale that worked its way into literature and history books and was unavoidable even in the fifties when i started reading.  since it likely never happened, it is really clear why zero evidence existed regarding its destyruction.

It was also originally raised in Spain and then was stationed in England and Northern Gaul.  It may well have been a recruiting issue and then disbanding made perfect sense.  We too disband perfectly good regiments.

 The actual conquest of Gaul caused legions to be raised in Spain and this makes for a consistent history. The following roman Civil War saw an explosion of legions ultimately to around sixty.  Most surplus legions were disbanded by Augustus, I am sure and this process likely dragged on for the most famous legions.

What actually happened to the Roman Ninth Legion that "vanished" from present day Scotland in the second century?

Astrid Ingmarsdottir

minor in history, experimental archaeologyUpdated 2y

The theory the IX Hispana was destroyed on campaign in the north of Roman Britain was first put forth by Theodore Mommsen in the 19th century, but archaeological finds since then have cast doubt on Mommsen’s theory. The last definite evidence of the Legion in Britain dates to 108 when it was involved in rebuilding the legionary fortress at York. Finds in 2015 of inscriptions on tiles and dedication stones seems to indicate that at least part of the legion and some of its most senior officers were on the continent after 108 AD. After about 120 the legion seems to disappear from the pages of history. Sometime between 210 AD and 230 AD, Dio Cassius drew up a list of 33 legions, and Legio IX Hispana is not among them, so all one can truly say is that between 120 and Dio Cassius, the legion was destroyed or disbanded. Where and when that took place is anybody’s guess for now unless new finds show are uncovered.