This led to less and less Roman citizens to fill the army's needs in order to maintain the empire they had accumulated. Hadrian had already started the process previous to this, the army was decentralized, immobilized, and was on its way to becoming a mercenary army. He began the policy of filling up the legions with provincials or peasants and permitting conquered people to settle Roman land in exchange for military service, when called upon. Therefore by the time of Marcus Aurelius, the army was composed to either composed of ignorant countrymen from remote parts of the empire, the poorer class, or foreigners. This cultivated an army that had little respect for or desire to protect the fatted calf that was Rome at that point. By 200 ad, the army knew its position and its power and was a driving force behind putting emperors into office as well as assassinating them quickly down the line. Later, they grew more and more apathetic to their original mission and became more and more tied to the political workings in Rome.
The political workings of Rome changed dramatically after the time of Marcus Aurelius mainly due to the military becoming more involved in the placement and removal of emperors as well as the steady decline in economy. By the second century, many cities were spending themselves into debt. Not only was there an adverse balance of trade, Rome was importing vastly more luxuries and exporting mainly currency, the taxed citizens were also supporting immense public works, buildings, bathhouses, and such. There were also the costs of the feasts, holidays, processions, and the games and spectacles of the amphitheatre, not to mention the dole that was handed out to the entire lower class. Slavery did not help this because it affected the free labor economy and its ability to be competitive within the market. Added to this was the same plague as above which meant there fewer people to tax.
