WILLIAM LOREN KATZ: In less than a year the battle for truth has lost three of its most innovative and stalwart voices, historians John Hope Franklin, Ivan Van Sertima and Howard Zinn. Each challenged aspects of the cheerfully bigoted narrative that has passed for history in schools, colleges, texts and the media. Each created works that made history by awakening millions of fellow citizens to a new host of heroic men and women whose daring contributions had been shamefully ignored.