In preparation for the time when the riders of Muspelheim, with the Giants and the evil powers of the Underworld, would declare war, Odin was preparing a number of defenders for Asgard. They were not the Æsir or the Vanir. They were mortal men, heroes chosen from amongst the dead on fields of battle in Midgard.
To choose the heroes, and to give victory to those who he wanted to have victory, Odin had battle maidens that went to the fields of war. Those battle maidens were beautiful and fearless. They were wise also, because Odin showed the Runes of Wisdom to them. They were named Valkyries, Choosers of the killed.
Those who were chosen on the fields of the killed were called the Einherjar. Odin made a great hall for them. Valhalla, the Hall of the killed, it was called. Valhalla had five hundred and forty doors, and out of each door eight hundred champions would pass. Every day the champions put on their armor and took their weapons down from the walls, and went out and battled with each other. All who were wounded were made whole again, and in peace and friendship they sat down to the feast that Odin prepared for them. Odin himself sat with his champions, drinking wine but eating no meat.
For meat the champions ate the flesh of the boar Sæhrimnir. Every day the boar was killed and cooked, and every morning it was whole again. For drink they had the mead that was made from the milk of the goat Heidrun, that ate the leaves of the tree Læradir. The Valkyries, the wise and fearless battle-maidens, went around, filling up their drinking-horns with the mead.
The youngest of all the battle-maidens was Brynhild. Nevertheless, Odin had shown more of the Runes of Wisdom to her than he had shown to any of her sisters. When the time came for Brynhild to journey down into Midgard he gave her a swan feather dress just as he had given before to the three Valkyrie sisters—Alvit, Olrun, and Hladgrun.
In the dazzling plumage of a swan the young battle maiden flew down from Asgard. She didn’t yet have to go to the battlefields. She looked for some water, and as she waited for instructions from Odin she found a lake that had golden sands on its shore, and as a maiden she bathed in it.
Near this lake lived a young hero whose name was Agnar. And one day as Agnar lay by the lake he saw a swan with dazzling plumage fly down to it. While she was in the reeds the swan-feather dress slipped off her, and Agnar saw the swan change into a maiden.
Her hair was so bright, so strong and all her movements were so swift, that he knew she was one of Odin’s battle maidens who give victory and choose the killed. Agnar was very daring, and he was determined to capture this battle maiden even though he would anger Odin by doing it.
He hid the swan feather dress that she had left in the reeds. When she came out of the water she could not fly away. Agnar gave the swan feather dress back to her, but she had to promise that she would be his battle maiden.
As they talked together the young Valkyrie saw in him a hero that someone from Asgard could help. Agnar was very brave and noble. Brynhild went with him as his battle maiden, and she told him about the Runes of Wisdom, and she showed him that the All-Father’s last hope was in the bravery of the heroes of the earth. He would make battle in defence of Asgard with the chosen from the killed for his Champions.
Brynhild was always with Agnar’s battalions. She hovered above the battles, her bright hair and flashing battle dress outshining the spears and swords and shields of the warriors.
But the gray bearded King Helmgunnar made war on the young Agnar. Odin favored the gray bearded King, and he promised the victory to him. Brynhild knew the will of Odin but she gave the victory to Agnar ,and not to Helmgunnar,.
Brynhild was doomed the instant she went against Odin’s will. She could never again come into Asgard. She was now a mortal woman, and the Norns began to spin the thread of her mortal destiny.
Odin All-Father was sad that the wisest of his battle maidens could never appear in Asgard nor walk by the benches at the feasts of his champions in Valhalla. He rode down on Sleipner to where Brynhild was. When he appeared in front of her it was his head, and not hers that was bowed down.
She knew then that the world of men was paying a bitter price for the strength that Asgard would have in the last battle. The bravest and noblest were being taken from Midgard to fill up the ranks of Odin’s champions and Brynhild’s heart was full of anger against the rulers of Asgard, and she did not care to be one of them.
Odin looked at his unbowed battle maiden, and said, “Is there anything you would have me do for you in your mortal life, Brynhild?”
“Nothing except this,” Brynhild answered, “that in my mortal life no one but a man without fear, the bravest hero in the world, may claim me for his wife.”
Odin bowed his head in thought. “I will do as you ask,” he said. “Only he who is without fear shall come near you.”
Then on the top of the mountain that is called Hindfell he had a Hall built that faced the south. Ten Dwarfs built it out of black stone. When the Hall was built he put round it a wall of fire.
Odin did more .He took a thorn of the Tree of Sleep and he pricked the battle maiden. Then, with her helmet on her head and the armor of the Valkyrie on her, he lifted Brynhild in his arms and carried her through the wall of fire. He laid her on the couch that was in the Hall. There she would lie in sleep until the hero who was without fear would ride through the flame and awaken her to the life of a mortal woman.
He said farewell to her and rode back to Asgard on Sleipner. He could not foresee what her fate would as a mortal woman. The fire he had left went rising and circling around the hall that the Dwarfs had built. For ages that fire would be a fence around where Brynhild, once a Valkyrie, lay in sleep.