Well it's the start of the war with Troy. Wellp, story time:

As you probably know, the gods of Olympus weren't really nice to eachother. So at one time the 3 main women had a little competition. They wanted to know who was the most beautiful. They let Paris decide. Paris was the youngest prince of Troy. The 3 godesses were Hera, Athena and Aphrodite. They each offered a gift. What the first two offered didn't really matter cause they lost. Aphrodite offered him the most beautiful woman of Greece: Helen (Or Helena). Now, there is just one tiny problem. Helen was already promised to the Macedonian king. Though Paris, the clever bastard that he is, kidnaps her and brings her to Troy. The Macedonian King was obviously furious and unleash the entire greek might upon Troy. Only to battle before its walls for many (8?) years. Until Odysseus comes up with this clever plan to fake a retreat and offer them a present. The rest is the common known legend of Troy.

So moral of the story? Youngest prince fell in love, kidnapped woman and unleash all hell on his city. Though some would say that Helen did love Paris.