Thomas R. Pegram, "Cullom, Shelby Moore," American National Biography Online, February 2000, http://www.anb.org/articles/05/05-00167.html.
As was the case with many late nineteenth-century public figures, the Civil War became the moral reference point for Cullom's political career. Unlike most others, he spent the war years as a Republican politician, not a soldier. Initially wary of the radical image of the new party, Cullom supported Millard Fillmore in 1856 and was elected to the state legislature on a combined Fillmore-Free Soil ticket. Then in 1858, he took the biggest (and perhaps the only) gamble of his career by hitching his fortunes to Lincoln and the Republicans. Cullom returned to the Illinois General Assembly in 1861 and served as Speaker of the lower house. He moved on to the U.S. House of Representatives in early 1865 and remained in office until 1871. Cullom returned to the Illinois General Assembly from 1873 to 1875, again holding the post of speaker from 1873 to 1874. Two terms as governor of Illinois followed between 1877 and 1883. Finally, in 1883 Cullom began the first of five consecutive terms in the U.S. Senate lasting until 1913. Throughout his tenure he clung to the image of Lincoln and the dictates of the Republican party. At the outset of his national political career, Cullom was a member of Lincoln's funeral party. During the intervening half-century, Cullom waved the bloody shirt, memorialized the "boys in blue," and became so closely linked with the GOP in Illinois that he developed into a visible symbol of the party's heroic past, "the man who looked like Lincoln."