Once upon a time, the river-god Achelous told Theseus and his friends, how he had fought Hercules, the son of Alcmena and Jove, for the hand of the lovely virgin Deianira, daughter of King Oeneus of Calydon.
Several suitors had approached Oeneus to claim the hand of fair Deianira. When Achelous and Hercules also laid their claims, all the other suitors promptly withdrew their claims. Achelous boasted of his kingdom of water that nourished the land of Calydon, while Hercules boasted his descent from Jove and the glory of his labours. Achelous asked Hercules to prove that he was the son of Jove, or confess that he was a son of shame. Hercules answered that his hand excelled his tongue, and full of unvented wrath, he challenged Achelous to a fight.
A fight ensued, and both stood their ground, defiant not to yield. With postures bent forward, pressing each other with their foreheads, they locked arms. Like in the pasture, two strong bulls rush at each other to gain some pretty cow, similarly, Hercules and Achelous fought for the beautiful Deianira. Hercules proved to be more mighty and forced Achelous to bite the sand. Achelous, using deception, changed his form to a snake. Hercules laughed and said that it was the pastime of his cradle days to kill snakes. He also recounted how he had killed the Lernaean snake, which grew two heads for every head that was destroyed. Then, extending his hand with great speed, Hercules grabbed the serpentine neck of Achelous and squeezed it. Unable to breathe, Achelous changed his form to a bull. Hercules, caught hold of the horns of the bull, and turned the horns so that the head of the bull turned, until the bull helplessly fell on the ground. Hercules with his mighty strength, tore off a horn. Achelous accepted defeat and Hercules won Deianira.
The Naiads preserved that horn, heaped it with flowers, delicious fruits, and called it as the sacred Horn of Plenty.
Excerpt from the book “Once Upon A Time-II: 150 Greek Mythology Stories” by Rajen Jani