Before he joined the Argo Heracles had completed his famous labours, each of which deserves its own story one day.
In Thebes, Heracles had married King Creon’s daughter, Megara. During a fit of madness caused by Hera, Heracles killed their children. After his madness had been cured with hellebore by Antikyreus, he realised what he had done and fled to the oracle at Delphi, without realising that the oracle was manipulated by Hera. He was directed to serve King Eurystheus for ten years and perform any task Eurystheus required. Eurystheus decided to give Heracles ten labours, but after completing them Heracles was cheated by Eurystheus who added two more, resulting in the twelve labours:
Slay the Nemean lion
Slay the nine-headed Lernaean hydra
Capture the golden hind of Artemis
Capture the Erymanthian boar
Clean the Augean stables in a single day
Slay the Stymphalian birds
Capture the Cretan bull
Steal the mares of Diomedes
Obtain the girdle of Hippolyta, queen of the Amazons
Obtain the cattle of the monster Geryon
Steal the apples of the Hesperides (he had the help of Atlas to pick them)
Capture and bring back Cerberus (the three-headed hound of Hades)
In future times, the Romans will call him Hercules. Many consider him the greatest of all heroes.