Perseus, Andromeda and the Dragon

Perseus, Andromeda and the Dragon
Long ago, Ethiopia was ruled by King Cepheus and Queen Cassiopeia, a vain woman who boasted that she was more beautiful than every one of the sea-nymph Nereids. Furious at this insult, the Daughters of the Sea complained to the god Poseidon, asking him to avenge them. He sent a dragon, who devastated the land and began devouring the young people of Ethiopia. The terrified population consulted the oracle Ammon, who told them that their only hope of deliverance was to hand over the beautiful Andromeda, daughter of the king and queen, to the dragon. Both monarchs were reluctant to surrender their daughter. Under pressure by their subjects, however, they finally agreed to the sacrifice.
The soldiers chained the maiden to a rock in the middle of the sea where the monster lived. Weeping and lamenting, the princess’s parents waited on the shore.
It so happened that young Perseus, the son of Zeus, was passing that way on his winged horse Pegasus. On seeing the desperate sovereigns, the hero, who had just killed the terrible Medusa, stopped to ask them what was wrong. Sobbing, the king and queen told him their story.
“We are waiting for the dragon to come up and devour our daughter,” they wailed. “If anybody can save her they will earn our gratitude, the hand of Andromeda, and the throne of Ethiopia.”
Perseus found their offer most tempting, as the beauty of the maiden chained to the rock was evident, and the King was rich and prosperous. So Perseus donned a magi helmet of invisibility, which had been given to him by Hades, King of the Underworld, then he slipped his arm into a shinning shield that has been a present from the goddess Athena-he was related to both these divinities. Brandishing a glittering diamond sword given to him by the god Hermes, Perseus rushed at the dragon.
Since the helmet made Perseus invisible, the monster was unable to defend himself. Andromeda naturally had no idea who was coming to her rescue. Perseus sliced through the dragon’s flesh until he reached the heart, and gouged it out (From the book of Mythology by Edith Hamilton it says that Perseus cut the sea-serpents head just like he did with Medusa, and other versions state that Perseus used Medusa’s head to destroy the dragon). Then he removed his magic helmet and revealed himself at last to the beautiful princess. With one stroke he cut through the chains that bound her to the rock, hoisted the maiden up onto his winged steed (most commonly known as Pegasus, which was conceived by Poseidon and Medusa and sprang from her body upon her death), and headed for the palace.
On reaching the royal palace, however, an unpleasant surprise was in store for him. Standing at the head of the army was Phineus, Andromeda’s former suitor, claiming her as his wife. Perseus, reluctant to give up his well-deserved reward, took out Medusa’s head from a linen bag and showed it to his enemies, who turned to stone at the sight.
Thus Perseus was able to marry the beautiful Andromeda unopposed. They had many beautiful children, one of him fathered Alcmena, the mother of the powerful Hercules. (Other versions never mentioned about Phineus and the struggle of Perseus getting married to Andromeda)

Gotten from: Dragon by Ciruelo
Mythology by Edith Hamilton
Pegasus from Encyclopedia Mythica Online