Richard James Oglesby is best known for introducing the rail-splitter image into Abraham Lincoln's successful presidential campaign of 1860, and in many ways his career ran parallel to Honest Abe's. This biography of the three-time governor of Illinois offers the first detailed view of a key figure in the great changes that swept Illinois and the country from the Jacksonian era through the Gilded Age.   Like Lincoln, Oglesby was born in Kentucky and spent most of his youth in central Illinois, apprenticing as a lawyer in Springfield and standing for election to the Illinois legislature, Congress, and U.S. Senate. Oglesby participated in the battles of Cerro Gordo and Vera Cruz during the Mexican-American War and made a small fortune in the gold rush of 1849. A superlative speaker, he ran unsuccessfully for Congress in a campaign that featured the Lincoln-Douglas debates of 1858, then was elected to the Illinois senate as Lincoln was being elected president.   When the Civil War came, Oglesby resigned his senate seat to lead a regiment of the Union Army. Critically wounded at the Battle of Corinth, he was promoted to major general before resigning his commission to run successfully for governor of Illinois. Oglesby was at Lincoln's deathbed and led the effort to build the sixteenth president's tomb in Springfield, delivering the major oration at its dedication. In the postwar years, Oglesby drew on his popularity, his association with the martyred Lincoln, and his extraordinary stump-speaking skills to rescue the Illinois Republican Party in a time of political crisis. In his third term as governor, Oglesby faced massive labor unrest in the aftermath of the Haymarket affair.   A mature and thoughtful biography, Lincoln's Rail-Splitter chronicles Oglesby's pivotal contribution to American political life while also providing a sensitive portrait of this able, energetic man.