Roman Empire
In the fourth century BC, Alexander the Great of Macedonia brought all these empires and dominions, in fact most of civilization known to the Western World, under his suzerainty in a series of rapid military conquests. In so doing, he carried to the highest point of development the art of war as it was practiced in the Greek city-states. He utilized the phalanx— a solid mass infantry formation using pikes as its cutting edge—as the Greeks had long done, but put far greater emphasis on heavy cavalry and contingents of archers and slingers to increase the maneuverability of his armies.
The Romans eventually fell heir to most of Alexander's empire and extended their conquests westward and northward to include present-day Spain, France, Belgium, and England, bringing these areas within the pale of Roman civilization. The Romans built on the achievements of Alexander and brought the art of war to its zenith in the ancient world. They perfected, in the legion, a tactical military unit of great maneuverability comparable in some respects to the modern division, performed remarkable feats of military engineering, and developed elaborate systems of fortification and siegecraft. For all their achievements, the Romans made no real progress in the development of new weapons.
Roman military institutions, like Roman political organization and economy, underwent progressive decay after the second century A.D. The Roman Empire in the west was succeeded first by a congeries of barbarian kingdoms and eventually by a highly decentralized political system known as feudalism, under which a multitude of warring nobles exercised authority over local areas of varying size.
SPQR was the "motto" and the official monogram of the Roman Republic, in the same way that "US" or "USA" represents the United States. SPQR stands for Senatus Populusque Romanus (in Latin) or Senate and People of Rome (in English). The Romans of classical antiquity were as enthusiastic for acronyms as modern Americans [BKs, KFCs, VCRs, DVDs, MRIs, EKGs and NASAs]. SPQR was inscribed on the base of the legion's eagle standards, like the regimental number for Napoleon's regiments, after the reforms of Marius [which created a professional military and did away with other legion symbols. SPQR seems to have been used in the Roman vexilla, though it was not used on flags in antiquity.
