Why was The Battle of Midway an important event in World War 2?

Because it cripple the Japanese carrier fleet by sinking the Akagi, Soryu and the Kaga and damaging the Hiyu at the cost of the USS Yorktown. The Japanese Invasion was aborted. Yes, Midway was a turning point. The Japanese lost aircraft carriers that they could not replace. The US lost some ships, but not nearly as many as the other side. It was also an indication that the Japanese codes had been broken and much intelligence was available. The US actually lured the Japanese to Midway and surprised them there.