The Twelve Labours of Heracles were a number of tasks that the mythical hero Heracles was told to complete by King Eurystheus. It all started when Hera, who loathed Heracles for he was a living example of her husband's infidelities, drove the hero mad, making him kill his wife Megara and his children. When he realised what he had done, he deeply regretted it and went to the Oracle of Delphi to ask for penance. There, he was told to serve Eurystheus, king of Tiryns, for twelve years; if he completed all tasks he would be given, he would become immortal. Although Heracles did not like this as he considered Eurystheus to be a lesser person than himself, he decided to follow the Oracle's advice.

When he arrived in Tiryns, Eurystheus initially asked Heracles to perform ten labours. These ten labours were:

1. to kill the Nemean Lion,

2. to kill the Lernaean Hydra,

3. to capture the Ceryneian Hind,

4. to capture the Erymanthian Boar,

5. to clean the stables of Augeas in one day,

6. to kill the Stymphalian Birds,

7. to capture the Cretan Bull,

8. to steal the Mares of Diomedes,

9. to steal the girdle of the queen of the Amazons, Hippolyta, and,

10. to steal the cattle of the monster Geryon.

Labour one: slaying the Nemean Lion

The Nemean lion was a terrible monster that roamed in the region of Nemea, capturing women as hostages and luring brave men to save them. When someone entered the lion's den and tried to free the woman, she would turn into the lion and eat the warrior alive. When Heracles arrived in a town of the region, he met a boy who asked him to kill the lion. He also told him that if Heracles killed the lion within a month, a lion would be sacrificed to Zeus; otherwise, the boy would sacrifice himself.

Heracles eventually found the lion roaming, and shot many arrows against it. Only then did he realise that the lion's skin was impenetrable, and that his arrows would be of no use. So, he decided to follow it to its den. There, he blocked one of the two entrances to the cave and entered through the other. Fumbling in the dark, Heracles managed to find the lion; he stun it with his club and then he strangled it with his bare hands.

After he had killed it, he thought of taking the impenetrable skin of the lion and use it as an armour. So, he managed to skin it with the help of the goddess Athena, who advised him to use the lion's claw to remove the pelt. Wearing the lion skin, Heracles entered the city on the thirtieth day. Upon seeing him, Eurystheus was initially horrified, for he feared the lion was roaming in the streets of the city.

Labour two: slaying the Lernaean Hydra

The Lernaean Hydra was a fearsome monster that lived in the swamp of the lake Lerna. It had been specifically raised by Hera to kill Heracles. The Hydra had nine heads, one of which was immortal and the rest were mortal.

The swamp was covered in a poisonous mist, so upon his arrival, Heracles put a cloth on his mouth and nose. To lure the Hydra out of its lair, the hero shot flaming arrows, achieving his intent. However, when he chopped one of the Hydra's heads, he realised in horror that two new heads would spring back.

At that point, the hero felt hopeless, so he asked for the help of his nephew, Iolaus. Iolaus, probably advised by the goddess Athena who favoured the hero, thought of an idea and put it in action; as soon as Heracles would chop one of the monster's heads, Iolaus would cauterise the stump with a firebrand. The plan was successful; no more heads would appear. Hera, angry that her side was losing the battle, sent a huge crab to distract Heracles, which he simply squashed under his foot. When it was time for the immortal head to be cut off, Heracles took a golden sword that Athenagave him, and using the same technique, the two heroes managed to kill the monster.

Before Heracles left, he dipped his arrows in the poisonous blood of the Hydra, one of which he later used to kill the centaur Nessus; this would later become Heracles' doom, as the hero died due to the Shirt of Nessus which was smeared in the centaur's blood containing some of Hydra's poison. Hera turned her slain monster into the constellation of the same name, while she transformed the crab into the constellation Cancer.

Eurystheus did not count the success of killing the hydra as one of the labours, using as an excuse the fact that Heracles was helped by Iolaus

.

Labour three: capturing the Ceryneian Hind

In their effort to mark an end to Heracles' successes, Eurystheus and Hera decided that the next task Heracles should do would be to capture the Ceryneian Hind. This was a sacred deer belonging to the goddess Artemis, and had golden antlers and hooves of bronze. It was believed that it was so fast that it could outrun a flying arrow.

Heracles made a real effort to track the animal. When he saw it, he followed it for a whole year through the lands of Greece, Thrace, Istria and the land of Hyperboreans. According to one version of the myth, he managed to capture the hind while it was sleeping. On his way back, Artemis and her twin brother Apollo appeared in front of Heracles. This task was given by Eurystheus, thinking that Heracles would cause the anger of the goddess and that she would punish him. However, when she appeared in front of him, Heracles asked for forgiveness, explaining to her that this was part of his penance for killing his wife and children. He also told her he would return the hind to her as soon as he showed it to Eurystheus. Artemisaccepted his apology and let him go.

When he returned to the king's court, Eurystheus told Heracles that the animal now belonged to him. Not forgetting his promise to the goddess, Heracles tricked Eurystheus by telling him he should take the animal himself and bring it to the palace. When Eurystheus came out to take the deer, the hero let it go and the animal ran back to Artemis. Heracles simply replied to Eurystheus that he was not been quick enough.

Labour four: capturing the Erymanthian Boar

The Erymanthian Boar was a giant animal living on Mount Erymanthos, which was dedicated to the goddess Artemis as well. Eurystheus thought that capturing this beast would be the perfect task that would lead to the hero's death. Heracles set forth on his journey to the mountain, but decided to stop by his friend's place, Pholus, a kind centaur. After eating together, Heracles asked his friend to open a jug of wine that he had, which attracted the other centaurs to Pholus' dwelling. Not knowing that wine was supposed to be watered down before being consumed, the centaurs quickly became drunk and attacked Heracles. The hero killed most of them by shooting his poisonous arrows against them; the centaurs that remained fled to Chiron's cave.

Pholus did not understand why these arrows were so lethal. Out of curiosity, he picked one up but it fell on his foot and poisoned him as well. Another version has it that one of the arrows mistakenly hit Chiron as well; although Chiron, being immortal, did not die, he could still feel an insufferable pain. Not able to withstand it, the wise centaur asked to be rid of the pain, exchanging his immortality as well as take the place of the Titan Prometheus, who was bound on the top of a mountain and his liver was being eaten daily by an eagle. Zeus accepted the exchange. Heraclesthen killed the eagle with one of his arrows, stopping the torture for Chiron.

Chiron advised Heracles how to catch the Erymanthian Boar; he told him that it would be very easy if the hero lured the boar into thick snow. Heracles followed Chiron's advice and captured the boar in no time. He then returned to Eurystheus, who upon seeing the creature was so scared that he hid himself in a large jar and asked Heracles to get rid of the animal.

Labour five: cleaning the stables of Augeas

King Augeas of Elis had a large number of cattle in his stables. All of them were blessed with perfect health and immortality, and being so lively, created a huge amount of dung. The stables of Augeas had never been cleaned in thirty years, and Eurystheus asked Heracles to clean them within a day. This task was set to stain Heracles' reputation as it was quite humiliating.

When Heracles reached Augeas' court, he asked for one tenth of the cattle if he managed to clean the stables in a day; the king agreed. The heromanaged to complete the task by diverting the rivers Alpheus and Peneus to pass through the stables and wash them out. Augeas refused to pay Heracles, and the hero took him to court, where he managed to win his claim, backed by Augeas' son, Phyleus. However, Phyleus and Heracles were both banished by Augeas before the court had ruled. Furious, Heracles returned to Elis, killed Augeas and handed the throne to Phyleus. This is when he was said to have founded the Olympic Games.

Although Heracles was successful, Eurystheus did not count it as a success, saying that it was the rivers that had done the work for him, and that he accepted payment for it.

Labour six: slaying the Stymphalian Birds

Eurystheus' next task to Heracles was to kill the Stymphalian birds, large flying monsters that ate humans with their bronze beaks; their wings were made of metallic feathers that could be thrown against their prey, while their dung was highly poisonous. They belonged to the god of war, Ares, and lived in the area of the lake Stymphalia, where they destroyed all the surrounding area and the towns.

Heracles was unable to go too deep into the swamp as he would eventually drown. Athena helped him by providing him with a rattle; the sound the rattle produced scared the birds and made them fly from their hiding place. While in the air, they were an easy target for Heracles, who shot many of them down with his poisonous arrows. The remaining birds flew away to plague other lands; in fact, they were later encountered by the Argonauts.

Labour seven: capturing the Cretan Bull

The seventh task Eurystheus gave to Heracles was to capture the Cretan Bull. This was a legendary creature that wreaked havoc on the island of Crete, destroying crops and land. After getting permission from King Minos, Heracles managed to catch the bull with his bare hands and sent it back to Eurystheus' court. Upon seeing the creature, Eurystheus hid in his jar and decided to sacrifice the animal to Hera. The goddess rejected the offer, as this would glorify Heracles' success even more. Instead, the animal was left free and went to the area of Marathon, getting the name Marathonian Bull. It was later caught by Theseus and was sacrificed to Athena and Apollo.

Labour eight: stealing the Mares of Diomedes

The Mares of Diomedes were fearsome animals that had been trained to eat human flesh. They were owned by Diomedes, king of Thrace. It was believed that due to their unnatural diet, the horses were seized with madness, uncontrollable and sometimes they even breathed fire. According to one source, Heracles brought a number of young men with him to help him with his task. After they managed to steal the animals, they were all chased by Diomedes and his army. Heracles told his companion Abderus to take care of the horses, while he was fighting Diomedes. Upon his return, Heracles realised that Abderus was devoured by the mares. Overcome with anger, Heracles fed Diomedes to his own horses, and later founded the city of Abdera in memory of his friend. After the horses were fed, they became calm and Heracles seized the opportunity to bind their mouths shut. He brought them back to Eurystheus, who either sacrificed them to Hera or left them roam free, as they had now become permanently calm.

Labour nine: stealing the girdle of Hippolyta

Admete, the daughter of Eurystheus, learned that Hippolyta, queen of the Amazons, had been given a girdle as a gift from her father, Ares, and wanted it for herself. So, Eurystheus decided to make this the ninth labour that Heracles would have to complete.

Heracles took some friends with him and set sail for the region of Themiscyra, where the Amazons dwelled. On their way there, they stopped at the island of Paros, where the sons of king Minos of Crete killed two of Heracles' friends. Furious, Heracles killed the sons of Minos and demanded that two of the inhabitants replace his dead comrades. Thus, two of Minos' grandsons joined the band, and they all set sail again.

After a brief stop at the court of Lycus, a friend of Heracles, they eventually reached the land of the Amazons. Hippolyta had heard of the glorious feats that Heracles had performed, and impressed, she immediately agreed to give her girdle. Heracles asked her to have lunch together on the ship and Hippolyta eagerly followed. At the same time, however, a disguised Hera went to the Amazons and started spreading rumours about Heracleswanting to abduct their queen. The Amazons decided to confront Heracles and rode towards the ship. Upon seeing them, Heracles thought that this had all been set up by Hippolyta and that she had no intention of handing over the girdle; so, he killed her, took the belt and set sail back to Tiryns.

Labour ten: stealing the cattle of Geryon

The tenth labour of Heracles was to steal the cattle of Geryon, who lived on the island of Erytheia, somewhere in the west. Heracles went on his quest, and he first had the cross the desert of Libya. At some point, having been so frustrated at the heat, he shot an arrow at the sun. Helios, the sun god, was so impressed by Heracles' courage, that he decided to help him by offering him his own golden chariot with which he sailed across the sea from west to east every night. Heracles hopped on the chariot and reached Erytheia overnight.

There, his first obstacle was the two-headed dog Orthrus, brother of Cerberus, the three-headed dog and guardian of the Underworld. One blow with Heracles' club was enough to kill Orthrus. Eurytion, the herdsman, heard what happened and when he tried to confront Heracles, he was killed in the same way. Geryon immediately grabbed his three shields and three spears, while wearing three helmets and attacked the hero. However, a powerful shot of an arrow from Heracles' bow was enough to pierce Geryon's forehead and sent him to his demise.

Bringing the cattle back to Tiryns was another task on its own. According to the Roman version of the story, Heracles took the road over the Aventine Hill where Rome would later be built on. There, a giant named Cacus stole some of the cattle, but they were later retrieved, called out by the animals remaining in the possession of Heracles. As an extra obstacle, Hera sent a gadfly to irritate the animals and scatter them. Heracles managed to get them back within a year. Before he reached Tiryns, though, Hera caused a flood that raised the level of a river so much that it could not be crossed. So, Heracles started piling stones into the river, and bridged the two riverbanks. He eventually reached Tiryns, where the cattle were sacrificed to the goddess.

Upon finishing the tenth labour, Eurystheus told Heracles that he considered two of the labours invalid; the Hydra was not slain by Heracles alone but was helped by Iolaus, while he accepted payment for the cleaning of the Augean Stables. So, two more labours had to be completed. These were:

       11. to steal the Hesperidean Apples,

       12. to capture Cerberus, guardian of the Underworld.

Labour eleven: stealing the apples from the garden of Hesperides

The Hesperides were nymphs of the sunset that tended a garden somewhere in the far western corner of the world. Heracles managed to capture the Old Man of the Sea, a shape-shifting sea deity, in order to find out the exact location of the garden. During this quest, Heracles also confronted the half-giant Antaeus, who was invincible by drawing power from his mother, Gaea (the earth), as long as he touched it. To kill him, Heracles held him high so his feet wouldn't touch the ground, and crushed him with his hands.

There are two versions on how Heracles managed to acquire the apples. One version has it that he reached the Hesperidean Garden, where he killed Ladon, the dragon guardian of the apples, and took the apples. According to another version, he came across Atlas, the Titan god who was condemned to hold the heavens on his shoulders. Atlas was also the father of the Hesperides, and thus had access to the garden at any time. Heracles persuaded Atlas to change places for a while, so that Atlas would fetch some of the apples. Atlas agreed and indeed took some of the apples. However, on his return, he decided he did not want to take the heavens back on his shoulders. Heracles tricked him and he said he would be keeping the heavens but wanted to adjust his cloak first. Atlas agreed to take the heavens back momentarily, but Heracles walked away taking the apples with him.

Labour twelve: capturing Cerberus, guardian of the Underworld

The final labour that Heracles had to complete was to capture Cerberus, the three-headed dog and guardian of the Underworld. Before going to the Underworld, Heracles decided to be initiated in the Eleusinian Mysteries, so that he would be taught how to travel alive from the world of the living to the realm of the dead and vice versa. He then went to Tanaerum, where one of the entrances to the Underworld lay, and was helped there by Athenaand Hermes. The goddess Hestia also helped him with negotiating with Charon, the boatman that guided the souls over the river Acheron towards the Underworld.

Once he reached the Underworld, he met Theseus and Pirithous, the two heroes that had been incarcerated in the Underworld by Hades for attempting to steal Persephone. According to one version of the story, snakes coiled around their legs and then turned into stone. A different version has it that the god of the Underworld feigned hospitality and invited them to a feast. However, the chairs on which the heroes were seated magically caused forgetfulness, thus keeping them there. Heracles pulled Theseus from his chair, managing to save him; however, part of his thigh was stuck to it, thus providing an explanation of the supposedly lean thighs of Athenians. When the hero tried to save Pirithous, though, the earth started trembling; it seems that because he desired Persephone for himself, it was so insulting that he was not allowed to leave.

Heracles found Hades and asked him to take Cerberus to the surface. The god agreed on the condition that no weapons should be used to achieve it. Heracles managed to subdue the dog with his hands and brought it on his back to Tiryns. Eurystheus fled in horror into his jar and asked Heraclesto take the monster back to the Underworld, releasing him from any other labours.

After the Twelve Labours were complete, Heracles decided to join Jason and the Argonauts in their attempt to obtain the Golden Fleece.

Source: https://www.greekmythology.com/Myths/The_Myths/Labours_of_Heracles/labours_of_heracles.html