What lead to the destruction of the city of Troy and what army defeated them?
The Trojan war happened so long ago that we do not know the details all that well. But there is archaeological evidence that the city did exists and that it did go through a time of war. Homer's Iliad is about this war. But as you can imagine, a poem is not a completely reliable historical account.
With this said, the war was between the Greeks and the Trojans. To the best of our knowledge, the kings of Greece got together and crossed the sea to Troy, which is in modern day Turkey and had a prolonged war. Eventually the Greeks were able to destroy the city. The way in which this was accomplished from a historical perspective is not known, but according to mythology it was through the ruse of a horse that Odysseus made. The horse contained Greek soldiers and when the horse was in the city, it was the basis for a Greek victory.
''I heard the city of Troy was discovered near Turkey.'' Samjazael
Well when I heard the city of Troy was discovered near Turkey it was quite compelling that they also find many other cities possible the biblical cities of Soddom and Gommorah which where found under ashes, and even signs of glass made from the mass explosion. If you like a good show that talks about it openly "which schools are sensitive about talking." is Ancient Aliens. Tells that we had guidance from an unknown entity which is cool, yet people tend to discredit it. It is a show with some facts, but they could have chosen more reliable people whom actually know what there talking about. I can say it a show that you learn about the mysteries of our unique world. It is one of many good documentaries, but I hate the reality shows on the History channel.