Marbod, or Marobodus should be treated as an exception - as his concept of a standardized army was way ahead of the usual "warring" most Germans had in mind. Particularly since Marobodus himself had spent time in Rome and witnessed how Romans organized armies to the concept of "total war".

The problem with the Germans was that they could manage to rally professional warriors in service of the warlord, and often in significant numbers. Their tactical prowess might perhaps even surpass that of the Romans in some occasions. But facing the Romans required something more than just trained soldiers. A standard element of armed forces in constant movement that stretched along all the tribes of Germania that would act under a unified strategic objective, was something the Germans just could not do.

There are debates about the Marian reforms, but evidently as the surrounding social/political struggles from the times of the Gracchus brothers to the end of the Civil war by Augustus would suggest, the German victories should be accounted to the decline of the quaility of the Roman military as much as strengthening of the Germans themselves. The economical destruction of the farming classes of everyday Romans had resulted in the conscription of the "proletari" - a class which was formerly exempt from military duties due to their low social status and poor morale. Marius' judgement is crucial and telling, as he imediately concluded that the standard soldiers currently in service could not be trusted when he was given the duty of driving off the Germans.

In a sense, one might be able to say the tribes fought as a means to live - a concept akin to the mercenary mentality. However, the Romans fought for the Republic - an abstract cause. And abstract causes have a way of making actions radical, swift, ruthless and efficient. When the social status of the people who are conscripted as soldiers were so poor that they could not find any 'cause' in the identity of Rome, they failed. And bam! Marius came up with a solution.