The fourth and last stage of organization was the Roman nation or people, formed, as stated, by the coalescence of three tribes. Externally the ultimate organization was manifested by a senate (_senatus_), a popular assembly (_comitia curiata_), and a general military commander (_rex_). It was further manifested by a city magistracy, by an army organization, and by a common national priesthood of different orders.[338]
A powerful city organization was from the first the central idea of their governmental and military systems, to which all areas beyond Rome remained provincial. Under the military democracy of Romulus, under the mixed democratical and aristocratical organization of the republic, and under the later imperialism it was a government with a great city in its centre, a perpetual nucleus, to which all additions by conquest were added as increments, instead of being made, with the city, common constituents of the government. Nothing precisely like this Roman organization, this Roman power, and the career of the Roman race, has appeared in the experience of mankind. It will ever remain the marvel of the ages.
As organized by Romulus they styled themselves the Roman People (_Populus Romanus_), which was perfectly exact. They had formed a gentile society and nothing more. But the rapid increase of numbers in the time of Romulus, and the still greater increase between this period and that of Servius Tullius, demonstrated the necessity for a fundamental change in the plan of government. Romulus and the wise men of his time had made the most of gentile institutions. We are indebted to his legislation for a grand attempt to establish upon the gentes a great national and military power; and thus for some knowledge of the character and structure of institutions which might otherwise have faded into obscurity, if they had not perished from remembrance. The rise of the Roman power upon gentile institutions was a remarkable event in human experience. It is not singular that the incidents that accompanied the movement should have come to us tinctured with romance, not to say enshrouded in fable. Rome came into existence through a happy conception, ascribed to Romulus, and adopted by his successors, of concentrating the largest possible number of gentes in a new city, under one government, and with their united military forces under one commander. Its objects were essentially military, to gain a supremacy in Italy, and it is not surprising that the organization took the form of a military democracy.