It was the Spartan warriors life-long training and close-knit battle units that made its army so fearsome. Like other Greeks, Spartans formed a group, phalanx, that could be seven lines deep. The precise shape of the phalanx depended upon the terrain, the enemy, and the battle plan.
Whatever, the Spartans tried to intimidate their opponents before the battle by elaborate preparations of their long hair, oiled into coils, under their helmets. their unique scarlet cloaks, and the self-selected totem painted on their shields. All Spartans bore the greek letter, Lambda (L). The also played a bagpipe style instrument to prepare themselves for battle, and perhaps unsettle their opponents.
They fought in a close unit, each man's shield extended over his left arm and positioned so that it covered the left side of the man fighting along side. The enemy saw the Spartan shield wall approach, first at a walk, then at a run, until the battle clash. Then it became a prolonged bloody shoving match until one side broke ranks and ran. Battles seldom lasted more that a few hours, and they fought in summer heat with full armor.
Spartans used their long lances/spears as the first weapon, with a sharpened bronze point on the bottom to allow soldiers to stab any fallen enemy as he lay on the ground. The first few rows of soldiers could project their spear points at the same time. Spartans also carried hand weapons, a short sword about 24-30 inches long, used for stabbing, and a small knife as a last weapon.
It was as much a contest of wills and nerve as a contest of arms, with orderly crowds of men shoving, pushing, and cutting into each other. You stood, or you fell and probably died, stabbed or even stomped to death. Surprisingly casualties were relatively light, but wounds were many, and Spartan nurses were renowned as the best in Greece.