Two weeks after the 7 December 1941 Japanese attack on Pearl Harbor, Yorktown transited the Panama Canal to reinforce the badly damaged Pacific Fleet. The carrier's first combat operation was the Marshalls-Gilberts raid in early February 1942.
Yorktown then steamed to the South Pacific, where she participated in a series of raids and other operations that climaxed in the Battle of Coral Sea in early May. In this action, in which she was damaged by enemy bombs, her planes attacked two Japanese aircraft carriers, helping to sink Shoho and damaging Shokaku.
Quick repairs at Pearl Harbor put Yorktown into good enough condition to participate in the Battle of Midway on 4-6 June 1942. During this great turning point of the Pacific War, her air group fatally damaged the Japanese aircraft carrier
Soryu and shared in the destruction of the carrier Hiryu and cruiser Mikuma. However, successive strikes by dive bombers and torpedo planes from Hiryu seriously damaged Yorktown, causing her abandonment during the afternoon of 4 June.
Two days later, while salvage efforts were underway, the Japanese submarine
I-168 torpedoed both the damaged carrier and the destroyer Hammann (DD-412), sinking the latter immediately and Yorktown shortly after daybreak on 7 June 1942. USS Yorktown's wreck was discovered and examined in May 1998, in surprisingly good condition after fifty-six years beneath more than three miles of sea water.
This page features a number of images of USS Yorktown, selected from the more extensive coverage linked below.
http://www.history.navy.mil/photos/sh-usn/usnsh-xz/cv5.htm