Literally any history and lots of rhetoric, poetry, and drama from ancient Greece and Rome. In the pre-Christian world, immortality was won through valor; wars were fought accordingly.

Diodorus:
>For the inheritance which the Spartans receive from their fathers is not wealth, as is the case with all other men, but an eagerness to die for the sake of liberty, so that they set all the good things which life can offer second to glory.

Caesar:
>“Why hesitate, Vorenus? What better opportunity do you want to prove your courage? Today shall decide between us.” With these words he advanced outside the fortification and rushed into the thickest place he could see in the enemy’s line.

Dionysius:
>“Ye gods of our ancestors, kindly guardians of this land, and ye other divinities, to whom the care of our fathers was allotted, and thou City, dearest to the gods of all cities, the city in which we received our birth and nurture, we shall defend you with our counsels, our words, our hands and our lives, and we are ready to suffer everything that Heaven and Fate shall bring."

Livy:
>“For what is there but death for a few men penned by an army in a ravine whence forest and mountain admit no escape? All that matters now is how we die: shall we offer our bodies helplessly, like cattle, to the knife, or, refusing passively to await the end shall we turn the strength of our anger to one last battle, till, daring and doing, we fall, drenched with their blood, amongst the heaped bodies and weapons of our dying enemies? Seek him out, the Lucanian traitor, the deserter! Seek and kill him! The man who before he dies sends Flavus as a victim down into Hell, will have great honour and a supreme consolation for his own death.”

Polybius:
>"When you go to meet the enemy, there are two objects only to keep before you, to conquer or to die. When men are inspired by that spirit, they will always master their adversaries, for when they enter the battle they have already chosen to sacrifice their lives.”

Sallust:
>“Is anything left for true men except to put an end to injustice, or to die valiantly, inasmuch as Nature has appointed one and the same end for all, even for those encased in iron, and no one awaits the final inevitability daring nothing, unless he is of a womanish temperament?”

Appian:
>Scipio maintained that while deliberation was proper when you were laying your plans, yet in an emergency, when so many men and their standards were in danger, nothing but reckless daring was of any use…He would either rescue them or gladly perish with them.