What significant event is referred to as the largest all-Marine battle in history?

The Battle of Iwo Jima is regarded as the largest all-Marine battle in history due to its scale and the pivotal role that Marine Corps forces played in the operation during World War II. Fought between February 19 and March 26, 1945, this battle involved over 100,000 U.S. Marines who were tasked with capturing the strategically significant island from the Japanese military. The battle was marked by intense and brutal fighting, with Marines facing fierce resistance from well-entrenched Japanese forces.

This operation was significant not only because of the number of Marines involved but also due to the high level of casualties on both sides, which highlighted the ferocity of the conflict. The eventual U.S. victory allowed for the establishment of air superiority needed for the following stages of the Pacific campaign. The iconic image of the raising of the flag on Mount Suribachi became a symbol of Marine valor and sacrifice, further solidifying the battle's importance in Marine Corps history.

The other choices reference important battles as well but do not involve the same level of Marine Corps participation as Iwo Jima. For instance, the Battle of Okinawa, while significant, involved joint operations between Marine and Army forces. The Battle of Chosin Reservoir was