Lincoln briefly worked as a clerk before joining the military in 1832, when he enlisted to fight in the Black Hawk War. He was quickly elected to be the captain of a company of volunteers that joined regulars under Colonel Zachary Taylor. However, he only served thirty days in this capacity before signing on as a private in the mounted Rangers and later joining the Independent Spy Corps. He saw no real action during his short stint in the military.
Lincoln decided on a political rather than a military career. He was defeated in his first attempt at office when he ran for the Illinois state legislature in 1832. He was appointed as postmaster of New Salem, Illinois, by Andrew Jackson and served from 1833 until 1836. During this time, he taught himself law and was admitted to the Illinois bar in 1837. At the same time, he was elected as a Whig to the Illinois legislature in 1834, where he served until 1842.
From 1847 to 1849, Lincoln was a member of the U.S. House of Representatives and was elected yet again to the state legislature in 1854. He helped form the Republican party in 1856 and resigned from the Illinois state legislature in 1858 when he was nominated to run for the U.S. Senate. In his acceptance speech for the nomination he gave his famous “house divided” speech in which he said, “A house divided against itself cannot stand. I believe this government cannot endure permanently half slave and half free.”
Lincoln's main opponent in the 1858 Senate race was Stephen Douglas. During the campaign, they debated each other seven times. While they agreed on many issues, they disagreed over the morality of slavery. While Douglas argued for popular sovereignty — allowing the citizens of each state or territory to decide if slavery would be legal within its borders — Lincoln did not believe that slavery should spread any further. Lincoln explained that while he was not asking for equality, he believed that African Americans should get the rights granted in the Declaration of Independence:life, liberty, and the pursuit of happiness. Even though Lincoln lost the Senate seat to Douglas, he became a national figure based on his oratory and debates.