The Trojan war is the legendary Greek siege of the city of Troy (or Troas), located on the close vicinity of the Dardanelles strait in present-day Turkey. The war took place around 1200 BC, when cities all across the eastern Mediterranean sea were being destroyed by various attackers -- including those of the Achaeans, so despite the version remembered in Greek mythology Troy was more likely taken by northern Greeks. The city itself was wealthy and had control of the Dardanelles, a point of great strategic and commercial importance (both Persian and Greek armies would later use this route to dominate the area), so was a prime target.
The epic begins with Eris, goddess of discord, throwing a golden apple inscripted with the words "for the fairest" at the wedding banquet of Peleus and the Nereid Thetis. This leads to the Judgement of Paris -- Paris, son of King Priam of Troy, is commissioned to give the apple to the most beautiful goddess and is asked to make a decision among Aphrodite, Hera and Athena. Aphrodite, the goddess of love, promises Paris the most beautiful woman of the world in exchange of the apple. Paris chooses Aphrodite, then goes to Greece to take beautiful Helen, wife of Menelaus, king of Sparta, to Troy. Greek armies besiege Troy with "1000 ships" in the lead of Agamemnon, king of Mycenae. Among the Greeks are heroes like Achilles, Patroclus, Ajax, Teucer, Nestor, Odysseus and Diomedes; among the Trojan are Hector, son of Priam and Paris' elder brother, and Aeneas.
The siege drags on for nine years. In the tenth year, which is described in Homer’s Iliad, Achilles kills Hector to avenge the death of his friend Patroclus. After Hector’s death, the Trojans win two more allies: Penthesilea, queen of the Amazons, and Memnon, king of Ethiopia. However, Achilles kills them both and in turn he is killed by Paris.
The city of Troy is at last captured by the following clever ploy, suggested by the ingenious Odysseus. The Greek forces seemingly accept their defeat and retreat to a near island, Tenedos (present-day Bozcaada in the opening of the Dardanelles strait), while a force of Greek warriors is to enter Troy by hiding in a large wooden horse (Trojan horse) built by Epeios. The horse is left behind apparently as a gift and despite warnings by Cassandra (Priam’s daughter) it is taken into the city. As the Trojans fall in a cozy sleep after drinking heavily during the celebrations of their victory, the Greek soldiers in the horse open the doors of the city and the waiting Greek forces capture Troy. King Priam and all of his sons are killed, the women are brought to Greece and the city is burned. Only a few Trojans escape, including Aeneas, who leads his companions to present-day Italy, eventually to found Rome (this part of the legend is told by Virgil in the Aeneid). The return of the Greek armies to Greece inspired many epic poems including Homer's Odyssey.
The story of the siege of Troy provided inspiration for many pieces of art other than those of Homer. Some of these are Troades by Euripides, Troilus & Criseyde by Chaucer and Les Troyens by Hector Berlioz (1855-1858).