In order to claim his birthright as king of Iolcus, Jason had to bring back the golden fleece from the city of Colchis. The fleece was owned by King Aeetes, and was guarded by a dragon that never slept. 

Jason gathered a group of heroes to set sail and retrieve the magical fleece. Among these heroes were Hercules, Theseus, Orpheus, Castor and Pollux. They set sail on the ship Argo, and thus called themselves the Argonauts.

The Argonauts encountered many dangers along their journey. 

Upon reaching Colchis, Jason met with King Aeetes. The king was reluctant to give up his fleece, but he agreed that Jason could have it if he passed the test that would be set before him. The test was for Jason to plant a field of dragon teeth. He was to plow the field with bulls that breath fire. The dragon teeth would then grow into an army of men, and he must defeat them. 

The king's daughter Medea fell in love with Jason. Being a sorceress, she offered to help him pass the test. She gave Jason a lotion that would protect him from the bulls' flames. She also told Jason to throw a rock into the center of the army that rose from the dragon teeth. He did so and the men turned and fought each other. After the test, Medea again used her sorcery to tame the dragon that guarded the golden fleece.

Jason returned to his home with the fleece, and was rightfully crowned king.