This was the ninth labour of Hercules, it was to obtain the belt of Hippolytes, Queen of the amazons (a tribe of warrior women).
The belt was a gift from the god Ares but King Eurytheus wanted to give it to his daughter.
When Hercules arraived, Hippolytes asked what he was doing there and Hercules told her about the quest and that he needed the belt. Hippolyte told him that she would just give it to him.
Unfortunately Hera started to spread rumors to the other Amazons that Hercules was attacking Hippolytes. The Amazons decided to defend thier leader and attack Hercules.
When Hercules saw a group of Amazons run towards him, he decided to run away to King Eurytheus with the belt before he had to fight (and kill) some of the Amazons