Gen. MacArthur had them on the run.

The dramatic "end-run" amphibious landing at Inchon had turned the tide in the Korean conflict. In October 1950, he planned to catch the retreating North Korean forces with another amphibious assault at Wonsan. But this time, the surprise was on MacArthur. The enemy had fled before his men could land.

Wonsan, however, was still historic. It was the last major combat amphibious assault attempted by the U.S.

Sixty years on, in a May 2010 speech, Defense Secretary Robert Gates questioned whether it would ever be "sensible to launch another major amphibious landing again." The Marine Corps, naturally, was apoplectic, since attacks from the sea are considered its core competency. It seemed as though their boss was publicly questioning their purpose.

But before he left office, Gates effectively answered his own rhetorical question in the affirmative. It happened when he ordered U.S. forces to intervene in Libya.

The backbone of the initial response: the Kearsarge Amphibious Ready Group. A three-ship formation led by the USS Kearsarge, the group includes some 2,000 marines, and their aviation assets -- Harrier attack jets, helicopters, and the V-22 Osprey that carry cargo and personnel.

Amphibious Ready Groups are like a Swiss Army knife. They can do a little bit of everything. At midnight on March 21, Harrier pilot "C.J." was eating lunch in the ship mess when he got word to launch for a combat search and rescue mission. A downed F-15 pilot was being chased by a small convoy of Gadhafi's thugs.

As C.J. jetted to the scene, he could hear the pilot breathlessly whispering for help as dogs barked and shots rang out in the background. Soon, C.J. delivered some well-placed ordnance that convinced the pilot's pursers to call it an early night.

Behind "C.J." came "Brillo," in a V-22. The V-22 can fly like a helicopter and a plane. Carrying a 15-man quick reaction force, Brillo's ship -- operating in "blackout" mode -- came in at 200 feet and 300 mph. He then flipped the engine and settled in a landing zone near the downed flyer. A minute later, the rescued pilot was headed back to the Kearsarge.

All in a day's work for the marines of the Kearsarge Amphibious Ready Group. During this nine-month deployment, the group had done a little bit of everything: supporting combat operations in Afghanistan, running counterpiracy ops in the Gulf of Aden, and training with forces from other countries in the Gulf States and the Horn of Africa. And then there was Libya. The group's area of operations spanned over 3,000 miles. On occasion, elements of the group were working the far ends of that envelope at the same time.

The logbook of the helicopter/dock landing ship Kearsarge answers the question of why we have amphibious forces. They are among the most responsive and cost-effective means to project U.S. power around the world. In fact, we don't have enough of them. The Pentagon should be buying more assets like the America-class amphibious assault ships, and speeding the purchase F-35Bs, the short-takeoff, vertical-landing replacements for aging Harriers.

Gates erred big-time in downplaying the value of an amphibious force. As one marine officer put it, "amphib ships and marines are mules." They get fed last, even though they do all the work. If we don't maintain a robust amphibious force, the barn may be empty when the next crisis comes.

James Jay Carafano is a senior research fellow for national security at the Heritage Foundation.