How old is English?
The question may be surprising but the answer is not obvious. Most migrating tribes at the end of the Roman
Empire wanted to go south where the climate is of course much warmer. However there are two known exceptions to that general
movement: the Franks, and the Anglo-Saxons. The migration of the Anglo-Saxons to Britain is
understandable because they were initially invited as, what is called by many authors, 'mercenaries'. The word
mercenary is however misleading: normally mercenaries are not a part of the legal army. Why would Britain hire
'mercenaries' while they could have built with the same money a regular British army?
The (Anglo-)Saxons were described by Gildas as 'foederatii' (federated troops). Historians have much debated about the exact meaning of the word. During the late Empire this word indicated all 'auxiliary' troops of the late-Roman army, in contrast to the dwindling numbers of 'classic' legionnaires. At the end of the Empire, they outnumbered the legionnaires, supposedly the bulk of the army. They came mostly from regions at the borders of the Roman Empire, which had obtained a great tax autonomy in exchange for a promise to provide troops at the service of the emperor. An important part of those cohorts was cavalry. Cavalry can move fast and can better tackle a dispersed enemy (raiders). The Empire increasingly lacked the financial resources to pay for powerful but slow legions. The word foederatii let some authors to put forward the idea that the Anglo-Saxons were in the beginning a part of the regular Roman army. They were supposed to be members of German auxiliary cohorts, recruited outside the Empire, and stationed in Britain by the Romans themselves. The underlying idea is that they later betrayed their masters. Can't one expect anything from those bloody Germans? This 'scientific' interpretation was clearly influenced by the 20th century wars against Germany.
Who were the best soldiers of the Empire? The Roman legionnaires without doubt, even at the very end of the empire. They were well trained, disciplined, and loyal to Rome. Former legionnaires would have been ideal to build a new army. Most legionnaires in Western Europe were Gaulish, Spanish or German in origin. And a surprising number of Britons. If the Gauls spoke the same Brythonic language as the Britons (as conventional history asserts) they would have been a natural choice as soldiers. So why were rude north Germans chosen instead? Why not the closer Franks? Why not the Britons themselves?
We also know that at least one lord in the east married a Frankish 'princess'. They must have tried to obtain help from the Franks. As Franks were Flemish or northern Belgians, they would have been a close by, obvious choice. The Franks had 'freed' themselves earlier from the Roman Empire (AD 352), and became officially 'federated' to the Empire. The main agreement was that they would stop all incursions of German 'tribes' passing through their country (Greater Flanders) who were heading for the southern parts of the Empire. The Franks were successful in doing so. They maintained for the purpose a sort of militia, not a Roman style professional army. They helped fighting Atilla (452) and later supported the northern Gallo-Roman governor in his struggle against German tribes. It is however evidently that they did so for their own sake also and that they were paid for the service. They were relatively rich, for they later (485 - under Clovis) had the means to conquer Gaul.