Many gruesome images of casualties become less sobering when one notices that they're photographs of re-creations from London's Imperial War Museum, stills from fictional movies or posed scenarios for training purposes. Still, Simon Adams's Eyewitness: World War I, part of an extensive Eyewitness series, provides an informative, picture-and-caption history lesson. Countless actual photos of trench life, tanks, rifles, uniforms, airplanes, artificial trees (for artillery observation posts) and other battle equipment and behavior are featured along with the re-creations.