Battle of Corellon and Gruumsh
Birth of the Elven race
The elven and Orc legends tell that birth of elves was a surprising event caused by a clash between Corellon Larethian and Gruumsh. This surprising event has been told in several ways among the different races, each with their own distinct flair.
The story of the battle takes two distinct forms, depending on does the teller side more with orcs of elves.
According to elves, Corellon Larethian was a great spirit, perfect and graceful, that danced and traveled through planes with thee all spirit of freedom, changing their form to fit whatever role they wished to take. Never settling on one form over others, they travelled and experienced every wonder life and existence and had to offer. They were mischievous, but a kind hearted spirit that lived their life to the fullest. Passionate, beautiful and mutable - that was how Corellon was, and most of the would accept this without question.
But Gruumsh, god of orcs did not accept such creature, and in great envy he felt angry towards Corellon's form and power. As a creature on mindless rage, Gruumsh attacked Corellon. Corellon, mildly annoyed by the hot headed orc, blinded him on one eye as a revenge.
Orcs, as one might think, have their own version of this story. According to orcs, Corellon Larethian was a flamboyant and insufferable prankster, causing harm where ever they went but with their magic and deceit they got themselves out of all the trouble and were foolishly praised by other gods that didn't see behind the betrayal. But Gruumsh, wise and perceptive, saw this and decided to give the bratty god a lesson.
Gruumsh would devise a trap for Corellon, and as the deceitful god would come close, he would through him with his spear and ambush the liar, and with every bit of blood the elf god spilt, he got weaker. The battle raged for ages, in some tellings across the planes, though orc tellings disagree did or did not Gruumsh lost his eye on this particular battle. Tellings do agree with the elven telling on the elves spawning from Corellon's blood.
Due to the nature of the myth, it is quite impossible to truly tell it's accuracy, but due to its prevalence, it is widely regarded as factual on its base components, though details are not agreed upon.