Old Norse, Lone Warriors
All the Einherjar in Odhinn's gardhr
slay each other with swords;
Fighting they fall, then fare from battle
and drain goblets together.
(From Vafthruthnismol in the Poetic Edda, translated by Grimnir Svithrirsson)
The Vikings of old feared death. Sort of. They thought that if they became old and sick and died in their beds, their souls would go to Hel, a cold, dark place, very similar to the Underworld where Orpheus found and lost his Eurydice. Their afterlife would be a life of cool shadow and forgetfulness.
If they died in battle, however, they would spend eternity in a more cheerful way. Either they would be picked up by Freya, the goddess of love, and taken to her hall, Sessrumnir. Or they would be fetched from the battlefield by Valkyries, women in armour on horses, who would bring them to Valhalla, the hall of Odin. Only the strongest, most daring warriors would be chosen by the Valkyries, for they had a great purpose. These men were called Einherjar.
Valhalla and the field outside, Idavollr, was described as little more than a Viking paradise. They got to spend the whole day fighting! And if some of they died, it didn't matter, because they would heal again by nightfall. Then they got to spend the whole night eating and drinking! The mead and the meat would never run out, for the divine goat Heidrun supplied a never-ending stream of mead from her udder, while the giant pig Særimnir had enough meat for everyone, and rose from the dead every time it had been slaughtered. Andrimnir was the cook who prepared the pork every day, and he had a pot called Eldrimnir in which to do it.¹
To complete the zoo, Gullinkambi, the rooster with the golden comb, would wake them up the next morning - totally un-hungover, of course - for more fighting and feasting.
All this fighting did serve a purpose. It was a preparation, a training for Ragnarok, the final battle that the Norns had foreseen. On that day, the Einherjar will march shoulder to shoulder out through Valhalla's 640 doors, 940 men abreast. The armies of Odin and Freya will meet the chaos forces of the Jotnar² and the bleak troops of Hel in one last, terrible battle.
In Håvamål, Odin speaks about how your cattle, your friends and your family will all die eventually. The words spoken about a brave person, however, will remain forever. The belief in the Einherjar may have something to do with this. Someone who lived a peaceful and cowardly life would soon be forgotten by the Vikings. But a Man who boldly went into battle would be sung of in lays and told of in sagas, and thus would go on to live forever.
¹ This pig story is very similar to the way Thor could slaughter his goats and eat them, only to have them restored the next day. It may therefore be a later confusion.
² I have seen these being referred to as frost giants and fire giants. In reality they were forces of chaos, malicious creatures, and the forerunners for trolls and jutuls. Frost and fire is what all life was made from, in the beginning, according to the Vikings.