You might find yourself surprised that poetry came out of a warrior-heavy society like Sparta but actually, Sparta was renowned in its own time for its poetry, as well as its music and dance. Sadly, only fragments of these work have survived the centuries. The only Startan works of poetry that survive to form a relative whole are those of Tyrtaeus. Tyrtaeus (Τυρταῖος Tyrtaios) was an Hellenic lyric poet from Sparta who composed verses around the time of the Second Messenian War, the date of which isn't clearly established, but sometime in the latter part of the seventh century BC. He is known especially for political and military elegies, exhorting Spartans to support the state authorities and to fight bravely against the Messenians, who had temporarily succeeded in wresting their estates from Spartan control. 

Tyrtaeus was predominantly an elegiac poet. The three longest fragments of surviving verse (fr. 10–12) are complete or virtually complete poems describing the ideal warrior and the disgrace or glory that attends his personal choices. Critics these days say it's not particularly good poetry but I enjoy it none the less. What follows was a marching song, for the soldiers to keep pace as they set off for war. Imagine how impressive that would have been to behold, if you will!

"Ye are of the lineage of the invincible Heracles; so be ye of good cheer; not yet is the head of Zeus turned away. Fear ye not a multitude of men, nor flinch, but let every man hold his shield straight towards the van, making Life his enemy and the black Spirits of Death dear as the rays of the sun. For ye know the destroying deeds of lamentable Ares, and well have learnt the disposition of woeful War; ye have tasted both of the fleeing and the pursuing, lads, and had more than your fill of either.
Those who abiding shoulder go with a will into the mellay and the van, of these are fewer slain, these save the people afterward; as for them that turn to fear, all their valour is lost —no man could tell in words each and all the ills that befall a man if he once come to dishonour. For pleasant it is in dreadful warfare to pierce the midriff of a flying man, and disgraced is the dead that lieth in the dust with a spear-point in his back.
So let each man bite his lip and abide firm-set astride upon the ground, covering with the belly of his broad buckler thighs and legs below and breast and shoulders above; let him brandish the massy spear in his right hand, let him wave the dire crest upon his head; let him learn how to fight by doing doughty deeds, and not stand shield in hand beyond the missiles.
Nay, let each man close the foe, and with his own long spear, or else with his sword, wound and take an enemy, and setting foot beside foot, resting shield against shield, crest beside crest, helm beside helm, fight his man breast to breast with sword or long spear in hand. And ye also, ye light-armed, crouch ye on either hand beneath the shield and fling your great hurlstones and throw against them your smooth javelins, in your place beside the men of heavier armament." [CURFRAG.tlg-0266.7]