In the summer of 1915, the Central Powers launched an offensive on the Eastern Front that they hoped would decide the war. It did not, of course. In June 1916, an Allied army under the command of Aleksei A. Brusilov decimated the Central Powers' gains of 1915. Brusilov's success brought Romania into the war, extinguished the offensive ability of the Habsburg armies, and forced Austria-Hungary into military dependence on and political subservience...