The destruction of the Carthaginian empire left Rome mistress of the western Mediterranean and by far the greatest power of the time. But this victory had only been attained after a tremendous struggle, the greatest probably that the ancient world ever witnessed, a struggle which called forth in Rome the patriotic virtues of courage, devotion, and self-sacrifice to a degree that aroused the admiration of subsequent generations, which drained her resources of men and treasure and which left ineffaceable scars upon the soil of Italy. One of the main factors in deciding the issue was the Roman command of the sea which Carthage never felt able to challenge seriously. Another was the larger citizen body of Rome, and the friendly relations between herself and her federate allies. This, with the system of universal military service, gave her a citizen soldiery which in morale and numbers was superior to the armies of Carthage. As long as Hannibal was in Italy Rome kept from year to year upwards of 100,000 men in the field. Once only, after the battle of Cannae, was she unable to replace her losses by the regular system of recruiting and had to arm 8000 slaves who were promised freedom as a reward for faithful service. On the other hand, Carthage had to raise her forces from mercenaries or from subject allies. As her resources dwindled the former became ever more difficult to obtain, while the demands made upon the latter caused revolts that cost much effort to subdue. It required the personality of a Hannibal to develop an _esprit de corps_ and discipline such as characterized his army in Italy. A third factor was the absence in the Roman commanders of the personal rivalries and lack of coöperation which so greatly hampered the Carthaginians in Spain and in Sicily. Still one must not be led into the error of supposing that the Carthaginians did not display tenacity and patriotism to a very high degree. The senatorial class especially distinguished itself by courage and ability, and there are no evidences of factional strife hampering the conduct of the war. The Romans overcame the disadvantage of the annual change of commanders-in-chief by the use of the proconsulship and pro-praetorship often long prorogued, whereby officers of ability retained year after year the command of the same armies. This system enabled them to develop such able generals as Metellus and the Scipios.