Which conflict involved intense ground fighting for Okinawa and Iwo Jima?

The conflict that involved intense ground fighting for Okinawa and Iwo Jima is World War II. This war was characterized by significant battles in the Pacific Theater, particularly as Allied forces fought against Japanese troops. The Battle of Iwo Jima, which took place in early 1945, was crucial for the United States as it sought to capture the island as a base for bombers targeting Japan. The fighting there was exceptionally fierce due to the island's strategic importance and the determination of Japanese forces to defend every inch of their territory.

Similarly, the Battle of Okinawa, which occurred later in 1945, was one of the largest amphibious assaults in the Pacific Theater and involved intense ground fighting. It was marked by heavy casualties on both sides and played a critical role in the Allied campaign leading toward the eventual invasion of the Japanese mainland.

In contrast, World War I primarily took place in Europe and did not involve the island-to-island combat seen in the Pacific. The Korean War and the Vietnam War, while involving significant ground conflicts, occurred in different geographical contexts and were not related to the intense battles at Iwo Jima and Okinawa during World War II.