At the battle of Leuctra, Epaminondas had to oppose with a small force of Thebans the far more numerous and hitherto invincible Spartan phalanx. The plain, parallel front attack here would have been equivalent to certain defeat, both wings being outflanked by the longer front of the enemy. Epaminondas, instead of advancing in line, formed his army into a deep column, and advanced against one wing of the Spartan phalanx, where the king had taken his station. He succeeded in breaking through the Spartan line at this, the decisive point; he then wheeled his troops round, and moving on either hand, he himself Outflanked the broken line, which could not form a new front without losing its tactical order. At the battle of Mantinea the Spartans formed their phalanx with a greater depth, but nevertheless the Theban column again broke through it. Agesilaus in Sparta, and Timotheus, Iphicrates, and Chabrias in Athens, also introduced changes in infantry tactics. Iphicrates improved the peltastae. They were armed with a small round target, strong linen corslet, and long spear of wood. Chabrias made the first ranks of the phalanx, when on the defensive, kneel down to receive the enemy's charge.

Full squares, and other columns, etc, were introduced, and accordingly deployments formed part of the elementary tactics. At the same time, greater attention was paid to light infantry of all kinds; several species of arms were borrowed from the barbarous and semi-barbarous neighbors of the Greeks, such as archers, mounted and on foot, slingers, etc. The majority of the soldiers of this period consisted of mercenaries. The wealthy citizens, instead of doing duty themselves, found it more convenient to pay for substitutes. The character of the phalanx, as the preeminently national portion of the army, in which the free citizens of the state only were admitted, thus suffered from this admixture of mercenaries who had no right of citizenship. Toward the approach of the Macedonian epoch, Greece and her colonies were as much a mart for soldiers of fortune and mercenaries as Switzerland in the 18th century. The Egyptian kings had at an early time formed a corps of Greek troops. Afterward the Persian king gave his army some steadiness by the admission of a body of Greek mercenaries. The chiefs of these bodies were regular condottieri, as much as those of Italy in the 15th century.

During this period warlike engines for throwing stones, darts, and incendiary projectiles were introduced, especially by the Athenians. Pericles already used some similar machines at the siege of Samos. Sieges were carried on by forming a line of contravallation, with ditch or parapet, round the place, investing it, and by the attempt to place the war engines in a commanding position near the walls. Mining was regularly made use of, to bring the walls down. At the assault, the column formed the synaspismus, the outer ranks holding their shields before them, and the inner ranks holding them over their heads, so as to form a roof (the testudo of the Romans) against the projectiles of the enemy. - While Greek skill was thus mainly directed toward shaping the flexible material of the mercenary bands into all sorts of novel and artificial formations, and in adopting or inventing new species of light troops, to the detriment of the ancient Doric heavy phalanx, which at that time alone could decide battles, a monarchy grew up which, adopting all real improvements, formed a body of heavy infantry of such colossal dimensions, that no army with which it came in contact could resist its shock. Philip of Macedon formed a standing army of about 30,000 infantry and 3,000 cavalry.

The main body of the army was an immense phalanx of some 16,000 or 18,000 men, formed upon the principle of the Spartan phalanx, but improved in armament. The small Grecian shield was replaced by the large oblong Carian buckler, and the moderate-sized spear by the Macedonian pike (sarissa) of 24 feet in length. The depth of this phalanx varied under Philip from 8 to 10, 12, and 24 men. With the tremendous length of the pikes, each of the six front ranks could, on levelling them, make the points project in front of the first rank. The regular advance of such a long front of from 1,000 to 2,000 men presupposes a great perfection of elementary drill, which in consequence was continually practised. Alexander completed this organization. His phalanx was normally 16,384 men strong, or 1,024 in front by 16 deep. The file (lachos) of 16 men was conducted by a lochagos, who stood in the front rank. Two files formed a dilochy, two of which made a tetrarchy, two of which a taxiarchy, two of which a xenagy or syntagma, 16 men in front by 16 deep. This was the unit of evolution, the march being made in columns of xenagies, 16 in front.

Sixteen xenagies (equal to eight pentecosiarchies, or four chili-archies, or two telarchies) formed a small phalanx, two of which a diphalangarchy, and four a tetraphalangarchy or phalanx properly so called. Every one of these subdivisions had its corresponding officer. The diphalangarchy of the right wing was called head, that of the left wing tail, or rear. Whenever extraordinary solidity was required, the left wing took station behind the right, forming 512 men in front by 32 in depth. On the other hand, by deploying the eight rear ranks on the left of the front ranks, the extent of front could be doubled, and the depth reduced to eight. The distances of ranks and files were similar to those of the Spartans, hut the close order was so compact that the single soldier in the middle of the phalanx could not turn. Intervals between the subdivisions of the phalanx were not allowed in battle; the whole formed one continuous line, charging en muraille. The phalanx was formed by Macedonian volunteers exclusively; though, after the conquest of Greece, Greeks also could enter it. The soldiers were all heavy-armed hoplitae.

Besides shield and pike, they carried a helmet and sword, although the hand-to-hand tight with the latter weapon cannot very often have been required after the charge of that forest of pikes. When the phalanx had to meet the Roman legion, the case indeed was different. The whole phalangite system, from the earliest Doric times down to the breaking up of the Macedonian empire, suffered from one great inconvenience; it wanted flexibility. Unless on a level and open plain, these long, deep lines could not move with order and regularity. Every obstacle in front forced it to form column, in which shape it was not prepared to act. Moreover, it had no second line or reserve. As soon, therefore, as it was met by an army formed in smaller bodies and adapted to turn obstacles of ground without breaking line, and disposed in several lines seconding each other, the phalanx could not help going into broken ground, where its new opponent completely cut it up. But to such opponents as Alexander had at Arbela, his two large phalanxes must have appeared invincible. Besides this heavy infantry of the line, Alexander had a guard of 6,000 hypanpis-tœ, still more heavily armed, with even larger bucklers and longer pikes.