What were the Greeks and Trojans fighting over?

On one level, the fight between the Greeks and the Trojans is fought over a woman, Helen of Troy. The gods became involved when Paris was approached to solve an argument between Aphrodite, Hera, and Athena..... he foolishly partricipated in solving their argument, one that he should never have gotten involved in.... choosing the most beautiful of the three. In the words of old.... Hell hath no fury like a woman scorned.... and in this case, it was two.