Which Marine Corps battle took place in April 1945 and was the last large action of World War II?

The Battle of Okinawa, which occurred from April to June 1945, is recognized as the last large-scale ground battle of World War II. This battle was significant due to its size and the intense fighting involved, representing one of the last major confrontations before the eventual surrender of Japan. The strategic objective of capturing Okinawa was essential for the Allies as it provided a staging area for the planned invasion of the Japanese mainland.

The Battle of Iwo Jima, while also a pivotal conflict in the Pacific theater, took place earlier in 1945, from February to March, and was not the last large action of the war. The Chosin Reservoir battle occurred during the Korean War in late 1950 and is therefore not relevant to World War II. The 2nd Battle of Khe Sanh also took place long after World War II, in 1967 during the Vietnam War. Therefore, the timing and context of the Okinawa battle make it the correct answer.