and began to plunder. The Roman commander, Publius Pomponius Secundus, and a legionary force supported by Roman cavalry recruited auxiliaries from the Vangiones and Nemetes. They attacked the Chatti from both sides and defeated them, and joyfully found and liberated Roman prisoners, including some from Varus' legions who had been held for 40 years. Arminius would continue to fight against the Romans, but the conflict remained a stalemate. He was poisoned by his fellow Germans in 21 AD, possibly by his own family, who feared his increasing autocracy. Impact on Roman expansion From the time of the rediscovery of Roman sources in the 15th century, the Battles of the Teutoburg Forest have been seen as a pivotal event resulting in the end of Roman expansion into northern Europe. This theory became prevalent in the 19th century, and formed an integral part of the mythology of German nationalism. More recently some scholars questioned this interpretation, advancing a number of reasons why the Rhine was a practical boundary for the Roman Empire, and more suitable than any other river in Germania. Logistically, armies on the Rhine could be supplied from the Mediterranean via the Rhône, Saône and Mosel, with a brief stretch of portage. Armies on the Elbe, on the other hand, would have to have been supplied either by extensive overland routes or ships travelling the hazardous Atlantic seas. Economically, the Rhine was already supporting towns and sizeable villages at the time of the Gallic conquest. Northern Germania was far less developed, possessed fewer villages, and had little food surplus and thus a far lesser capacity for tribute. Thus the Rhine was both significantly more accessible from Rome and better suited to supply sizeable garrisons than the regions beyond. There were also practical reasons to fall back from the limits of Augustus' expansionism in this region. The Romans were mostly interested in conquering areas that had a high degree of self-sufficiency which could provide a tax base for them to extract from. Most of Germania Magna did not have the higher level of urbanism at this time as in comparison with some Celtic Gallic settlements, which were in many ways already integrated into the Roman trade network in the case of southern Gaul. In a cost/benefit analysis, the prestige to be gained by conquering more territory was outweighed by the lack of financial benefits accorded to conquest. The Teutoburg Forest myth