World War I era
An amphibious assault took place at the beaches of Veracruz, Mexico in 1914, when the United States Navy attacked and occupied the city as result of the Tampico Affair.
During World War I, amphibious warfare was still in its infancy: tactics and equipment were rudimentary and required much improvisation.
During this period, British Royal Marine Light Infantry (merged with the Royal Marine Artillery in the 1920s to form the Royal Marines) were used primarily as naval parties onboard Royal Navy warships to maintain discipline and man ships’ guns. The RMLI joined a new Royal Navy division—the Royal Naval Division—formed in 1914 to fight on land; however, throughout the conflict, army units were depended upon to provide the bulk—if not all—of troops used in amphibious landings.
The first amphibious assault of the war ended in disaster in 1914. A large British Indian Army force was directed to launch an amphibious assault on Tanga, German East Africa. British actions prior to the assault, however, alerted the Germans to prepare to repel an invasion. The Indian forces suffered heavy casualties when they advanced on the city, forcing them to withdraw back to their boats, leaving much of their equipment behind.
The Allied invasion against the Ottoman Empire at the Battle of Gallipoli in 1915 proved even more disastrous than Tanga, in part due to incompetence at the high command strata.
Soldiers were landed via open, oared whaleboats and tugs at Anzac Cove and Helles. At V Beach, Helles, the landing troops—inexperienced at amphibious landings—were effectively slaughtered by the Ottoman defenders, most not even making it out of their landing craft. The Royal Dublin Fusiliers, for example, lost almost all their officers, including their commander, and suffered over 500 casualties.
In a second landing at Suvla in August, the forerunner of modern landing craft—the armoured ‘Beetle’—was first used by the British.
On the 11th of October 1917 German land and naval forces launched an amphibious assault, code named Operation Albion, on the islands of Saaremaa (Ösel), Hiiumaa (Dagö) and Muhu (Moon), that controlled the entrance to the Gulf of Riga. By the end of the month German forces had successfully overrun the islands forcing the Russians to abandon them with the loss of some 20,000 troops, 100 guns and the Pre-dreadnought battleship Slava. The capture of the islands opened a route for German naval forces into the Gulf of Finland threatening the city of Petrograd, a fact that contributed to the cessation of hostilities on the Eastern front
Interwar period
The Alhucemas Landing on 8 September 1925, performed by a Spanish-French coalition against rebel Kabilas in the north of Morocco, was a landing where tanks were used for the first time; air naval gunfire support were employed by the landing forces, directed by spotting personnel with communication devices.
Floating depots were organized with medical, water, ammunition and food supplies, to be dispatched ashore when needed. The barges used in this landing were the surviving “K” boats from Gallipoli. But in this case, the landings were performed against a prepared, defended in force positions.
In 1938, Japanese forces attacked Chinese defenders over the Yangtze River at the Battle of Wuhan.