The extraordinary demands of the Punic Wars, in addition to a shortage of manpower, exposed the tactical weaknesses of the manipular legion, at least in the short term. In 217 BC, near the beginning of the Second Punic War, Rome was forced to effectively ignore its long-standing principle that its soldiers must be both citizens and property owners. During the 2nd century BC, Roman territory saw an overall decline in population, partially due to the huge losses incurred during various wars. This was accompanied by severe social stresses and the greater collapse of the middle classes. As a result, the Roman state was forced to arm its soldiers at the expense of the state, which it had not had to do in the past.

During what century did Roman controlled areas see a decline in their populations?