Seniores and Iuniores (again)

[Mark Hygate]

.....

Surely you could say the same thing about the English army in the last millennium.

Somewhat different environment, however...

For the 'English', post-1066, there are few major military defeats, certainly where entire units are wiped out - and not then reconstituted.  From the Horse & Musket period onwards, you then also have an organisational issue to factor in - where Regiments often sent only a single battalion somewhere, with a second staying at home.  Or even one like the 95th Rifles that sent Battalions and sometimes only independant companies all over the place - but the 'unit' stayed.

The long service and longevity of several of the Roman legions, must also be noted against the 'Legions' (major formation at, perhaps, to be considered 'Regimental' or 'Brigade' level) that we know almost nothing more about than they were defeated/destroyed and never replaced (eg XVII, XVIII & XVIIII) - it wasn't until 100 years later that the Roman Army even increased once more to the 30 Legion level.