The Washington Post, February 24, 1985 IN WHICH WAR was the term "Gook" invented? When did American soldiers conduct their first body count and pioneer the use of the "water cure" to persuade Asian guerrillas to betray their comrades? After which battle did a young rifleman write home to the folks in Kingston, New York, "I am in my glory when I can sight my gun on some dark skin and pull the trigger"? Modern as it all sounds, the answer is not Vietnam, or even Korea or World War II. The American conquest of the Philippines barely rates a mention in school history books, usually as a cryptic footnote to the short war which President William McKinley and publisher William Randolph Hearst waged on Spain in 1898 for the independence of Cuba and the circulation of Hearst's newspapers. Yet 126,458 Americans fought in the Philippines between 1898 and 1902, of whom 4,234 died, while 16,000 Filipinos died in battle and another 200,000 in "reconcentration camp." There were in addition massacres of civilians in reprisal for guerrilla attacks and similar sideshows all too familiar in subsequent Asian wars. The story of how, and why America liberated the Philippines from Spain and then took the islands back from their inhabitants two weeks later is a complicated one, already well told in one of the classics of American historiography, Leon Wolff's Little Brown Brother, published in 1960. But the writing of history is never finished, and David Haward Bain has managed another fine book on the subject, not disagreeing with Wolff's conclusions, but making them fresh and vivid for a generation which has seen yet another Asian war.