Andrew Johnson (December 29, 1808 –  July 31, 1875) was the 17th president of the United States, serving from 1865 to 1869. He assumed the presidency as he was vice president at the time of the assassination of Abraham Lincoln. In 1862, Lincoln appointed him as military governor of Tennessee after most of it had been retaken. In 1864, Johnson was a logical choice as running mate for Lincoln, who wished to send a message of national unity in his re-election campaign; their ticket easily won. In his second term, Johnson supported the Polk administration's decision to fight the Mexican War, seen by some Northerners as an attempt to gain territory to expand slavery westward, and opposed the Wilmot Proviso, a proposal to ban slavery in any territory gained from Mexico.