The Trojan War was a war in Greek mythology that was fought between the Greeks and the Trojans.
The Goddess of Discord, Eris, had been left out of a banquet. Feeling resentful, she decided to create mischief among the guests. She threw an apple, called the Apple of Discord, into the hall; the apple was marked "for the fairest". As expected, every goddess wanted to claim the title, but eventually it was narrowed down to Athena, Aphrodite, and Hera. Zeus told them to let Paris judge their worthiness.
The three goddesses appeared before Paris and bribed him. Athena promised him victory over the Greeks; Hera promised to make him Lord of Europe and Asia; and Aphrodite promised him the fairest woman in the world. Paris chose Aphrodite's offer and gave her the apple. This famous event is known as the Judgment of Paris, and it set off the Trojan War.
Helen was a beautiful maiden and the fairest in the world, and every suitor dreamed of marrying her. So her father, King Tyndareus, exacted an oath that no one would try and kidnap Helen and they would try to keep her safe. She was given to Menelaus, Agamemnon's brother, who was King of Sparta.
After giving the Apple of Discord to Aphrodite, Paris was led to Helen to a banquet. Menelaus, trusting Paris, left for Crete. Paris then kidnapped Helen. As such, Menelaus came back to find Helen gone, and he called for all of Greece to help. Two important figures, however, were missing: Odysseus and Achilles. Odysseus pretended to be insane, but he was found out after a messenger put his son at risk. Achilles was later found out; he was made to dress in women's clothing, but Odysseus found him fingering swords, and he knew it was him.
The Greeks set sail for Troy. During the journey a terrible occurrence caused a terrible north wind to blow upon the ships. Artemis was enraged at a hare being killed by the Greeks, and she demanded a sacrifice by killing Agamemnon's eldest daughter, Iphigenia. Reluctantly, the Greeks abided and she was sacrificed; the wind stopped but the Greeks knew they had a price to pay soon.
Eventually the Greeks arrived at Troy, and the war immediately engaged. Both sides were impressive, and victory wavered for nine years. Finally, conflict arose between two Greeks: Achilles and Agamemnon. Agamemnon had taken Chryseis, and Chryses, her father, begged for her back. Agamemnon refused, so Chryses prayed to Apollo for help. Apollo thus sent a terrible plague upon the Greek army, killing several men.
Achilles called an assembly and insisted that something had to be done to appease Apollo. Calchas the prophet told Achilles the exact reason for the plague, that Chryseis had been kidnapped. This angered Agamemnon, but he returned her to her father. In exchange, however, he took Achilles's own daughter, Briseis.
Achilles's mother, Thetis, was just as angry as he was, and she implored upon Zeus to let the Trojans take the victory to spite the Greeks. Zeus was reluctant, as he was on the Greeks' side. Zeus sent a deceptive dream to Agamemnon, urging him to attack.
Following the dream, the Greeks fiercely attacked the Trojans while Achilles was in his tent. A face-off occurred between Paris and Menelaus. Menelaus was on the verge of victory until Aphrodite intervened and saved Paris, hiding him. The Greeks declared that this counted as their own win, and they demanded that the Trojans give Helen back. However, Hera was determined that Troy must be destroyed, so Athena on her side persuaded Pandarus to shoot Menelaus. Thus the battle wagered on.
Due to Achilles's absence, Ajax and Diomedes were the highest-ranked fighters. It came down to Diomedes and Hector, Trojan King Priam's son. When Diomedes faced him, he saw the War God Ares was on Hector's side, so he backed out. However, Hera and Athena intervened once more and caused Diomedes to wound Ares.