The first tactical system which the Romans encountered, fundamentally different from the earlier Italo-Hellenic system, was the Celtic sword-phalanx.

It is not impossible that the subdivision of the army and the intervals between the maniples in front were arranged with a view to resist, as they did resist, its first and only dangerous charge; and it accords with this hypothesis that Marcus Furius Camillus, the most celebrated Roman general of the Gallic epoch, is presented in various detached notices as the reformer of the Roman military system.

The further traditions associated with the Samnite and Pyrrhic wars are neither sufficiently accredited, nor can they with certainty be duly arranged;( 23) although it is in itself probable that the prolonged Samnite mountain warfare exercised a lasting influence on the individual development of the Roman soldier, and that the struggle with one of the first masters of the art of war, belonging to the school of the great Alexander, effected an improvement in the technical features of the Roman military system.
National Economy-- The Farmers-- Farming of Estates In the national economy agriculture was, and continued to be, the social and political basis both of the Roman community and of the new Italian state.

The common assembly and the army consisted of Roman farmers; what as soldiers they had acquired by the sword, they secured as colonists by the plough.

The insolvency of the middle class of landholders gave rise to the formidable internal crises of the third and fourth centuries, amidst which it seemed as if the young republic could not but be destroyed.