Germanic Urbanisation & Infrastructure Post Augustus

[Nathan Ross]

Gone was the free farmer-soldier of earlier, republican times... the notion of military service as an honour or privilege... there was no incentive to fight or indeed to do anything to further the aims of a society which effectively excluded them from sharing in its benefits.

An honour-driven warrior culture and patriotic military service works very well in defending a small city state, but once that state expands it's hard to maintain. The legionaries of Caesar did not fight for the glory of Rome or the honour of the senate - they fought for the gold of Rome and the honour of Caesar. Roman armies of the 1st century AD had no qualms fighting other Roman armies in civil wars. By the age of Severus there were few connections between the troops and the citizens they were supposedly 'fighting for'.

Empires of any size and duration will quickly end up exchanging patriotic citizen-service for paid professional armies.

it was certainly inglorious but surely not "highly effective". 

It was effective for a while, I would say, providing there was a mobile foederati force on hand as well - Stilicho used the strategy against Alaric in 401-2 and Radagaisus in 405-6, and was victorious on both occasions. It did not work later in Gaul or Italy because the foederati - the 'hammer' to the 'anvil' of the fortified cities - were not present. Cities could hold out far longer, on the whole, than roving barbarian armies who lack siege equipment, so it was a safer strategy than risking everything on an open battle. And western emperors were often keener to maintain their military strength to see off usurpers than they were to tackle barbarians who could usually be bought off in the end.

Unfortunately the strategy also relies on having a civilian and landowning rural population able and willing to accept vast amounts of ravaging while the enemy are coaxed into a position where they can be effectively neutralised. In Gaul, and later in Spain, this turned out not to be the case - with the imperial armies unable to rid the provinces of the invaders, many provincials seem to have taken matters into their own hands, either as bagaudae and suchlike or by trying to cut some sort of deal with the invaders themselves. And that - rather than straightforward military defeat - was what led to the unravelling of the western empire.