Final answer:
The first manual dedicated to amphibious operations following the interwar period was the Landing Force Manual, which was crucial for successful assaults like the D-Day invasion on June 6, 1944, in Normandy, France.
Step-by-step explanation:
During the interwar period after World War I, there was recognition of the need for specialized training and strategy development for amphibious operations. The first manual dedicated to such operations, following experiences from earlier conflicts such as the Banana Wars and the landing at Gallipoli during World War I, was the Landing Force Manual. This manual laid out tactics, procedures, and logistical considerations essential for successfully conducting amphibious assaults, which would prove pivotal during World War II, particularly in landings such as the D-Day invasion of Normandy, France, on June 6, 1944.
The large-scale offensive on D-Day was the culmination of extensive planning and training in amphibious warfare. It involved a massive deployment of Allied forces using thousands of landing craft to overwhelm the German defenses. The strategies and tactics outlined in the Landing Force Manual were instrumental in the execution of this and subsequent amphibious operations in the Pacific theater, such as island hopping towards Tokyo and the battles for the Mariana Islands.