"This is only the first loss which the Nation would suffer in the destruction or eclipse of its Marine Corps—and it is a loss which cannot be compensated by the part-time assignment of Army troops to naval purposes, for it is not the genius of a national Army to act as a highly mobile fighting force in instant readiness. Armies are ponderous. They organize and prepare for operations with care and deliberation and they have great staying power. While those are unquestionably admirable virtues, they still are not the characteristics which go to make up an effective mobile, amphibious fighting force, in peace or war—a force ready to act as a part of the fleet at any time. This, indeed, is the fundamental difference between the Marines and the Army and the effect of this difference has been manifest many times. There is a continuous record of instances in our national history where the Army could not move at all, or could not move soon enough to satisfy the needs of the situation—Cuba in 1906, Vera Cruz in 1914, Iceland in 1941, and Guadalcanal in 1942, are only a few typical examples which demonstrate the point I make. In each case, the Army arrived on the scene only after the objective sought by the United States had been accomplished by Marines. This is not offered in criticism of our Army, but as a factual statement of the effect of basic functional differences. These may be summarized in a simple statement—that no matter how hard it tries, a great national Army cannot be a specialist Marine Corps and still be an Army."
January 1, 1970
https://en.wikiquote.org/wiki/United_States_Marine_Corps