The Savage Wars of Peace by Max Boot

“And the marines reaped plenty of collateral benefits from their five years spent chasing Sandino. A generation of marines gained invaluable experience in small unit operations, combat patrolling, close air support, the use of automatic weapons, and jungle fighting. ‘The Constabulary Detachment, where I saw it in both Haiti and Nicaragua, was the best school the Marine Corps has ever devised,’ Chesty Puller proclaimed near the end of his life.
”A few years later many of the Nicaragua veterans—Puller, ‘Red Mike’ Edson, Herman Hanneken, and others—would put those lessons to good use on Guadalcanal, in the first major U.S. offensive of World War II. If, as the Duke of Wellington once claimed, the Battle of Waterloo was won on the playing fields of Eton, then it might be said with equal justice that the Pacific campaign in World War II was won in the jungles of Nicaragua.”

-Max Boot, 2002