Lyman Trumbull was born in Colchester, Connecticut on 12th October, 1813. After attending Bacon Academy he worked as a school teacher in Connecticut (1829-1833).
Trumbull studied law and after being admitted to the bar worked as a lawyer in Belleville, Illinois. A member of the Democratic Party, Trumbull served in the state legislature (1840-41), secretary of State of Illinois (1841-43) and a justice of the supreme court of Illinois (1848-53).
After the outbreak of the American Civil War Trumbull introduced a Confiscation Act that was passed by Congress that enabled the Union Army to free slaves in Confederate territory. However, the law provided no enforcement mechanism and was ineffective.
In July, 1861, Trumbull was a member of a group of politicians, including Benjamin Wade, James Grimes, and Zachariah Chandler, who witnessed the Battle of Bull Run. The battle was a disaster for the Union forces and at one stage Trumbull came close to being captured by the Confederate Army. After arriving back in Washington, Trumbull was one of those who led the attack on the incompetence of the leadership of the Union Army.
Trumbull was a leading supporter of the Civil Rights Bill that was designed to protect freed slaves from Southern Black Codes (laws that placed severe restrictions on freed slaves such as prohibiting their right to vote, forbidding them to sit on juries, limiting their right to testify against white men, carrying weapons in public places and working in certain occupations).
When Andrew Johnson vetoed the Civil Rights Bill in March, 1866, Trumbull made an impassioned speech against the president. However, he doubted the legality of trying to impeach Johnson and voted against the measure.
In 1872 Trumbull supported the more radical Horace Greeley against the official Republican Party candidate, Ulysses S. Grant. After leaving the Senate in March, 1873 Trumbull returned to work as a lawyer in Chicago. He remained active in politics and in 1880 was unsuccessful bid for the post of Governor of Illinois. Lyman Trumbull died in Chicago on 25th June, 1896.