Amphibious warfare encompasses the set of techniques, equipment, specialized units, and methods of training needed to move troops across water, and deliver them to land, ready for immediate combat. The best-known examples are attacks from the sea, but crossing rivers and other inland bodies of water still is important.
Amphibious warfare went through many generations of development. Large-scale landings directly against defended shore targets, however, really only existed in the middle of the twentieth century. Effective techniques did not even begin to exist until after the First World War; there were bloody learning experiences, during the Second World War, at the Dieppe Raid and Battle of Tarawa. While there had been immense technical improvements at the Battle of Normandy, there was still desperate fighting, and both successes and failures in new tactics and equipment. The Battle of Inchon, in the Korean War, was probably the last large major frontal attack in the history of amphibious warfare.
Defenses became too lethal, but, simultaneously, new methods using air assault, hovercraft, and other methods were developed, in the 1950s, to go around strong defenses. Questions are being asked, however, if 21st century defenses are too dangerous to amphibious ships.  U.S. Secretary of Defense Robert Gates posed it as:
We have to take a hard look at where it would be necessary or sensible to launch another major amphibious landing again—especially as advances in antiship systems keep pushing the potential launch point further from shore. On a more basic level, in the 21st century, what kind of amphibious capability do we really need to deal with the most likely scenarios, and then how much?
Attacking from the sea was certainly nothing new, as in the legend of William the Conqueror:
William, in descending from his ship, missed his footing and fell full length upon the sand. Anticipating the effect of such an evil omen on his superstitious followers, he exclaimed, "By the splendour of God, I have taken seisin of England! -- I hold its earth in my hands!"
While there were many small-force landings from conventional boats, efficient techniques for large-scale amphibious landings did not develop until after the First World War; the lack of such techniques proved disastrous in the Gallipoli Campaign.
Beginnings of modern technique
As a specific doctrine, amphibious warfare largely was developed by the United States Marine Corps in the 1920s and 1930s. The iconic result of the early doctrine was having large numbers of landing craft, lowered from transports into the water and moving in waves toward the target. Watching the landing force at the Battle of Iwo Jima, an observer likened it to "all the cats in the world having kittens." Often while under fire, the landing craft would beach themselves, dropping a ramp for troops to rush ashore, while the landing craft retracted from the shore and going back for more loads.
Advanced Base Operations in Micronesia
Battle of Inchon
Types of water crossing
Sea movement from distant points
Battle of Guadalcanal
Local movement using the sea
After crossing the Rhine, Gen. George S. Patton Jr.
as the history-minded
Patton stepped off the last pontoon, he deliberately stumbled onto the soft ground in an imitation of William the Conqueror (who is supposed to have said as he fell flat on his face as he stepped out of his boat, "See, I have taken England with both hands") Patton, kneeling, steadied himself against the bank with both hands and, rising, opened his fingers to let two handfuls of earth fall,
exclaiming: "Thus William the Conqueror!"
Actions against defended landing areas
Avoiding frontal amphibious attack
Much WWII effort went into shore bombardment, to suppress the defenses, although with only moderate success. Indeed, later in the war, the Japanese doctrine was to let the assault force land unmolested, but then to trap them in preplanned killing zones.
Senior German leaders did not agree on the defensive approach to defense against amphibious operations, Marshal Erwin Rommel wanting to hit hard on the beaches, while Gerd von Rundstedt believed in letting the troops come ashore, but then to strike at them with armored divisions. The situation in Europe, however, was much different than the Pacific islands; Rommel believed, correctly in retrospect, that land-based Allied airpower would prevent the armored units from manuevering.
Nevertheless, amphibious specialists looked for alternatives to frontal beach assaults. The current doctrine is to isolate a landing area with helicopter-borne troops, then bring in heavier equipment with air cushion vehicles still of significant range, and then to use traditional landing craft only after a beachhead was secured.
Logistics is always a challenge to amphibious operations. Originally, it was assumed that large operations would have to capture a port, but the Dieppe Raid of WWII established, even with 1940s defenses, that was infeasible. For the Normandy invasion, innovative methods, created a temporary port on a bare beach. Today, once a beach can be secured, if a port is not available, prepositioning ships deliver equipment effectively using customized but industrial-speed techniques.
- Robert O. Work and F. G. Hoffman (November 2010), "Hitting the Beach in the 21st Century", U.S. Naval Institute Proceedings Magazine
- Remarks as Delivered by Secretary of Defense Robert M. Gates, Navy League Sea-Air-Space Exposition, 3 May 2010
- Planché, J.R. (1874), William The Conqueror and His Companions. King Harold and Bosham., Tinsley Brothers
- Ellis, Earl H. (1921), Advanced Base Operations in Micronesia
- Corbett, Karen L. (1990), Marine Corps Amphibious Doctrine - The Gallipoli Connection
- Robert M. Browning, Jr., The Coast Guard at Iwo Jima, United States Coast Guard
- "After The Battle: Crossing the Rhine: Patton's Hat-Trick", After The Battle (no. 16): 40, 1977