Why did the war in the book "The Iliad" begin?

It started with a wedding. The wedding of the mortal king Peleus and the Nereid Thetis was attended by almost all of the gods. Eris, goddess of strife and mischief, was left out. Outraged, the goddess appeared at the wedding and threw into the air a golden apple. Inscribed in the apple are the words: "To the fairest of them all". The goddesses Hera, Athena, and Aphrodite all tried to take the apple and claim the title. They turned to Zeus to choose between the three of them who should have the apple. Zeus asked the counsel of the prince Paris. Hera bribed Paris with the power in the world to conquer everything he likes. Athena offered him wisdom and knowledge. Aphrodite offered him the most beautiful mortal woman in the world, Helen of Troy. Paris chose Aphrodite. Aphrodite told him that if he would go to the land of Troy and abduct Helen, she would choose him over her husband Menelaus. Paris then traveled to Troy pretending it was a social visit. When Menelaus was away, Paris abducted Helen and stole half of the king's treasures. Menelaus, of course, was outraged. He waged war against the Greeks.