A painstaking revisionist examination of the life and times of Rodrigo Diaz, a.k.a. El Cid (c. 1043-1099), the Christian warrior-knight who spearheaded the 11th-century Spanish revolt against the Moors. Fletcher (Medieval History/England's Univ. of York) plausibly interprets the few surviving records about this myth-enshrouded figure to uncover a much less romantic personality: a mercenary who ""was his own man and fought for his own profit,"" even if that sometimes meant serving Moslems. This aristocrat survived that political tumult resulting from fracturing Moorish unity and began a remarkable skein of military victories that left him the rich, independent ruler of Valencia. Opportunistic, greedy, brutal (he had one Moslem enemy burned alive), yet courageous, the Diaz of history was as mesmerizing in his way as the pious knight of Poema de Mio Cid and Corneille's tragedy Le Cid. With dry academic wit, Fletcher recounts how Spain's centuries-long need for a hero transformed this soldier of fortune into a patriotic icon (""The cult of dead heroes at their tombs is too perennial [from Hector to Elvis Presley] for any individual manifestation of it to be neatly docketed and explained by the historian""). His analysis of other medieval aristocratic warrior-heroes is also well done. Yet he largely squanders his opportunity for a riveting biography by dwelling at tedious, even confusing, length in the book's first half on his hero's social and political milieu. Well researched and impeccably argued, this history unfortunately lacks narrative drive, limiting its appeal more to academics than to the wider audience it should have enjoyed with such a compelling subject.