The 1860 Republican National Convention was a presidential nominating convention of the Republican Party of the United States, held in Chicago, Illinois from May 16 to 18, 1860. The 2 strongest candidates for the nomination were former U.S. Representative Abraham Lincoln of Illinois and the former Governor of New York and U.S. Senator William H. Seward. Seward was generally expected to get the nomination. When voting for the nomination began, Seward led on the first ballot with Lincoln a distant second. But on the second ballot, the Pennsylvania delegation switched to Lincoln, putting him in a near-tie with Seward. On the third ballot many additional delegates switched to Lincoln, and he won the party's nomination.

More Info: www.wikipedia.org