Book excerpt: Conventional military wisdom holds that the amphibious assault against a defended beach is the most difficult of all military operations--yet modern amphibious landings have been almost universally successful. This apparent contradiction is fully explored in this first look at 20th-century amphibious warfare from the perspective of the defender. The author, Col. Theodore L. Gatchel, USMC (Ret.), examines amphibious operations from Gallipoli to the Falkland Islands to determine why the defenders were unable to prevent the attackers from landing or to throw them back into the sea after they had fought their way ashore. He places the reader in the defenders' shoes as such epic battles as Normandy, Iwo Jima, and Inchon are planned and fought, and then uses these cases to explain why the defenders were unable to successfully defend against enemy landings. A practitioner, teacher, and student of amphibious warfare, Colonel Gatchel follows those explanations with speculations on how a defender today might try to stop a landing and on the implications of such actions for future amphibious operations.