The Trojan War was a mythical (or semi-mythical) war that took place between the Greeks and the Trojans in Asia Minor (modern-day Turkey). The war provides the basis for three of the most famous Greek and Latin epic poems: Homer's Iliad recounts some of the events that brought the war to its close, and both Homer's Odyssey and Virgil's Aeneid tell the stories of various characters in the war's aftermath.
According to the myth, the war started when Paris, a prince of Troy, abducted Helen, the wife of the Greek king Menelaus (Menelaus was not the king of all of Greece, as the country did not exist at the time; rather, he was king of one the Greek city-states). Paris had been promised Helen by the goddess Aphrodite, in return for choosing her as the fairest in a competition between three goddesses.
The Greeks were incensed by this affront, and Menelaus and his brother Agamemnon, the most powerful of all the Greek kings, declared war on Troy. Following this, all the other kings of Greece had to join the war as well because of agreements they had with each other (similar to the outbreak of the First World War).
The Greeks amassed a mighty fleet and set sail for Troy. Initially they did battle with the Trojans and their allies in various parts of Asia Minor, but eventually the war reached a stalemate with the Greeks in control of most of the land and the Trojans besieged inside their city, which seemed impregnable. It is this siege scenario that provides the setting for most of the stories about the Trojan War.
The Trojan Horse
After a stalemate lasting ten years, with the Greeks unable to enter Troy and the Trojans unable to send the Greeks home, the cunning Greek king Odysseus devised an ingenious plan. The Greeks pretended to surrender and sail home, leaving behind only an enormous wooden horse, which appeared to be a peace offering. The Trojans brought the horse inside the city, and at nightfall a horde of Greek warriors burst out of it, caught their enemies off guard and sacked the city.
Although it does not form part of the Iliad, this story is the most famous part of the Trojan War, and the phrase Trojan Horse is now applied to anything that appears benign until it has gained another's trust, and then reveals itself as malicious and damaging. The proverb 'Beware of Greeks bearing gifts', a warning against naivety, also has its origins here.
At the end of the war, Troy was completely destroyed. A few Trojans managed to escape, led by Aeneas; they eventually settled in modern-day Italy (as told in the Aeneid), and their descendents supposedly founded the city of Rome.
Although the Greeks won the war, ten years of combat in a foreign land took their toll and many returned to find trouble at home or worse. Agamemnon, leader of the Greeks, was killed by his wife on arriving home. Most famously, Odysseus was not able to return home for another ten years, as told in the Odyssey.