Was Helen a true cause of the Trojan war?

Answer 1

I suppose it depends on what you mean by "true".

According to the story, Helen had been courted by just about every king in Greece. Her father, Tyndareus, was worried that war would break out among the suitors should he choose, so Odysseus, who felt he had little chance of being chosen proposed a solution. All of the suitors would give an oath, before the selection was made, that he would come to the defense of the chosen husband against anyone who would quarrel with him. This was why the whole of Greece went to war with Menelaus when Helen was abducted.

That said, the truth of it was probably a little different. The abduction of Helen, if it happened at all, would have been little more than an excuse for the Greeks to subdue a major rival in the region. They had already subdued the Minoans (thanks in part to a series of natural disasters), and the subjugation of Troy would have secured them as the major power in the region until the arrival of the Persians.