How Did The First Organized Military Form, And Under What Nation.?

Since humans nearly universally form armies of young warriors, it no doubt precedes civilization. Civilization increased population so army size increased but it is a pretty fair bet that we have been expanding our range with warfare against our neighbors long before civilization started. All human civilizations had warriors if they had competitors nearby.

“More than 5,000 years ago, in the wars between civilizations of the Middle East, foot soldiers were the main combatants….The first significant change was brought about by the domestication of the horse in about 2000 BC. Early horses were not strong enough to be ridden by armored warriors, but they could pull chariots. With the appearance of the chariot, the foot soldier took a back seat in the military hierarchy for several hundred years.As has always proved true with the ownership of horses, charioteering was expensive and thereby limited to a small, wealthy segment of the population. By 1000 BC the infantry was once again the main fighting force, but it was soon overtaken again by the horse–this time for riding. The mounted warrior, forerunner of the knight of the Middle Ages, made his appearance about 900 BC. The only significant interruption in the ascendancy of cavalry came during the time of Rome’s expansion, when the legion–armed foot soldiers–was the chief combatant. In the era of Rome’s decline the empire was overcome by barbarians quite accustomed to horses. Many of these barbarians eventually became defenders of the Eastern, or Byzantine, Empire; for several centuries they helped prevent a complete takeover by Islam…The resurgence of the foot soldier came with the introduction of gunpowder…The use of interchangeable parts made possible uniformity in the quality of rifles and handguns, as Samuel Colt demonstrated. Rifles became more accurate at long range. Repeating weapons were improved, and the machine gun was invented in time for use in the American Civil War…Throughout most of the centuries of warfare, military men have devised their own strategies and insisted they were the best. In the 4th century BC the Chinese general Sun-tzu wrote ‘The Art of War’, one of the earliest compilations on strategy….Much later Napoleon decided there were at least 115 maxims needed to guide generals….Tactics of attack. Direct frontal attack is the simplest way to go into battle. It can also be the most disastrous. During the Second Punic War the armies of Carthage met those of Rome at Cannae, Italy, in 216 BC. The Roman forces were in line formation. Hannibal, the Carthaginian general, had the center of his infantry in a crescent formation opposite. As the Romans attacked, Hannibal allowed this infantry crescent to reverse itself. Into the space created by the reversal of the crescent ran the Roman troops, only to be enveloped by the Carthaginians as they swooped around the Roman flanks in what quickly turned from a crescent into a circle. At the battle of Marathon in 490 BC during the Persian Wars, the Greek commander Miltiades had dealt with the Persian ground troops in almost the same manner.”http://history-world.org/warfare%20Intro…
The word “army” comes from:
army
c.1386, from O.Fr. armée, from M.L. armata “armed force,” from L. armata, fem. of armatus, pp. of armare “to arm,” lit. “act of arming,” related to arma “tools, arms,” from PIE *ar- “to fit together.”
So for it to start out meaning “to fit together” and go to interchangable parts in 5000 years is interesting.http://www.etymonline.com/index.php?l=a&…

When the word organized is mentioned, my first instinct is to go with the romans. While it’s true that other civilizations had had armies long before Rome came about, their armies, as mentioned by bravozulu, were nothing more than conscripted citizens. The Marian reform of the Roman army brought about the first professional standing army. Although long before that Carthage had formed another type of professional army, one consisting solely of mercenaries.