English to Spanish Social Sciences Government / Politics Libro de Noam Chomsky: Deterring Democracy

"While at his post, Reston had performed *****yeoman service******** in the cause of freedom, as when he took pride in the U.S. contribution to the huge slaughter in Indonesia in 1965, and explained in properly somber tones, as U.S. military force was demolishing what was left of the South Vietnamese countryside in late 1967, that this was being done "on the principle that military power shall not compel South Vietnam to do what it does not want to do," out of our loyalty to "the deepest conviction of Western civilization," namely, that "the individual belongs not to the state but to his Creator," and thus has rights that "no magistrate or political force may violate."

Chomsky habla de James Reston, "long the leading political thinker of the New York Times...".

El Webster's define "yeoman" (como adjetivo): characterized by laborious effort and great usefulness

Pero, aparte de la única frase que se me ocurre ("prestó servicios muy útiles"), me gustaría saber si hay una frase más característica o específica para expresar esta idea de "yeoman service" en español.

Mil gracias.