Nearly every country seems to have a hero that saved (what they conceive as) their Nation from extinction during what we call the Dark Ages, and, in some cases, much later in time.
Turnbull refers to 'The Bruce" as 'A New Arthur' for Scotland----hmmmm--do we really know how many times Scotland has been invaded and by whom.
Previously mentioned was the invasion of Caledonia by the Scotti, Celts from Ireland. Again, a by product of this "Irish" aggressiveness remains in the story of Tristan and Isolde. The Dark age "Kingdom" of Cornwall does seem to have been the subject of raiders from "ireland' if the concept and word were in existence at the time.
So, now we now why Caledonia is called Scotland and not 'Pictland'.
It seems Charlemagne would be consider the "Arthur" of France. His Empire consisted of presesent day France and considerable portion of present Western germany.
The Empire had, at that time, many brands of Germans, including the Gepids and perhaps many of the races with whom Caesar fought. The French word for Germans (Allemagne) comes from the Tribe called the Allemani.
The word France, of course, is taken from the absolutely teutonic tribe called the Franks.
Thus Charles would have had Franks, Goths, Gepids, Celtic Gauls, Huns, Romanized Gauls, Italian, multi ethinic descendants of the Coloni where the Legion veterans were settled, (thus the name Cologne in Present day Germany) and Belgicae at a very minimum to deal with.,
The Arthur of Ireland was Called Brian Boru. He has a rich history and was King of Leinster in present day Ireland. Dublin itself was held by the Danes.
Brian consolidated Ireland, defeated the Danes at the battle of Clontarf in 1037 only to die in that battle and have his sons "preside' over the disintegration of their Father's united "Ireland".
Arminius is sometime considered the Arthur of Germany because of his distruction of three Casearian/Augustan Legiones in Western Germany in 9 AD. (Legios XVII, XVIII and XIX-to young to have received cognomen)
But the Cherusci, Herman's tribe, liked him little and it is interesting that his own brother, called Flavus, was a Romanized Cherucsi/German and, at least once, had to be physically restrained form attacking his brother during Parleys. Herman died, as I recall, while still on the run. Hugh may corect me on the point.
Germanicus, perhaps as able a General as any Rome produced, recovered the three Eagles lost in the Varian disaster.
Italy's Arthur might well be Giuseppe Garibaldi who united Italy under the house of Victor Emmanuel of Sardinia. One hates to go into modern times, but the holy Roman Empire did not fall quickly. Again, one hates to go into modern times, but Italy remained divided into many 'Kingdoms' dating back to the Dark ages which remained separate until modern times.
Charlemagne himself was Crowned with The Iron Crown of the Lombards.
The Arthur of Judea (called that by the Romans) can well be considered Judas Maccabeus who expelled the 'Successor' forces and rule of the Seleucid Empire.
Perhaps Germany's ttrue Arthur was Otto Von Bismark-perhaps Frederick the Great?
For Spain "El Cid" (Al Sayyid) Roderigo Diaz De Bivar.
For Russia perhaps the mythic hero Ilya Muromets, about whom less is known by me than I might suggest to know about Arthur Himself.
More nations have there Arthurian type heroes, but I wished to put some forward for comment in the hopes that others can suggest heroes of this stature for other nations I do not know about.
Rome itself had several men named "New Fathers of Rome" including Camillus, Marius, and Julius Caesar.
"All Enlightenment Gratefully Accepted"