Lyman Trumbull was born in Colchester, Connecticut, on October 12, 1813. His parents were Benjamin Trumbull and Elizabeth Mather, and Lyman had at least two brothers: Benjamin, Jr., and George. After receiving his education at the local Bacon Academy, Trumbull went to Georgia to seek employment as a schoolteacher. During this time, he began to study law and after moving to Belleville, Illinois, in 1837, he began his work in the legal profession. By 1840, Trumbull had established his own local practice. He was elected that year to the Illinois state legislature as a Democrat, though he soon moved on, replacing Stephen Douglas as Illinois secretary of state; he served in that capacity from 1841 until his resignation in 1843. In 1848, after an unsuccessful run for the United States House of Representatives in the election of 1846, Trumbull became a judge for the Illinois Supreme Court, where he served until 1855.
In 1855 Trumbull began his congressional career, using his outrage over the Kansas-Nebraska act to gain the support of a faction of the split Democratic Party, and winning the election for United States senator for the state of Illinois, besting a group of challengers that included Abraham Lincoln. During his time in congress, Trumbull became an outspoken opponent of slavery, and in 1857 left the Democratic Party for the nascent Republican Party. He gained notoriety as a fervent opponent of Stephen A. Douglas on the in Kansas-Nebraska issue, and supported the efforts of Abraham Lincoln and the Union cause during the Civil War. After the war, Trumbull continued to be a prominent voice in the government, authoring the final draft of the Thirteenth Amendment, but began to drift away from prevailing sentiments within the Republican Party. Trumbull was one of a handful of Republican senators who voted to acquit Andrew Johnson during his impeachment trial, and briefly considered, but ultimately abandoned, a run for the Presidency in 1872. In 1873, on the expiration of his term, Trumbull left the Senate and returned to Illinois to practice law in Chicago, where his family had remained throughout the war. Trumbull died on June 25, 1896.
Lyman Trumbull had two wives, the first of which was Julia M. Jayne (1824-1868) of Springfield, Illinois, whom he married on June 21, 1843. Julia, whose ancestors were from Massachusetts, had been a bridesmaid for the wedding of Abraham and Mary Todd Lincoln. She diedI in 1868. The couple had three surviving sons: Walter (1846-1891), Perry (c. 1841-1902), and Henry. Walter married Hannah Mather Slater in 1876, and had two surviving sons: Walter S. (b. 1879) and Charles L. (b. 1884). Perry married Mary Caroline Peck in 1879; they had four children: Julia, Edward, Charles, and Selden.
In 1877, Trumbull married his cousin, Mary Jane Ingraham (1843-1914), the daughter of Almira Mather Ingraham and John D. Ingraham of Saybrook, Connecticut. Lyman and Mary also had two daughters, neither of whom survived to adulthood: Mae (1878-1884) and Alma (1883-1894).
Mary's mother, Almira W. Mather (1823-1908), was descended from the New York Mather family, and had at least one brother, Samuel Rogers Selden Mather. Her husband, John Dickinson Ingraham, was a sailor; the couple had four children: John Dickinson Ingraham, Jr. (1839-1875), Mary Jane (who married Lyman Trumbull), Annie Elizabeth (1847-1865), and Julia Trumbull (1853-1918). John D. Ingraham, Jr., was a sailor like his father, and served in the navy during the Civil War. Julia married George S. Rankin (1845-1892), who was also a mariner, and the two had at least one daughter Annie, who died in childhood. The couple lived in Saybrook, Connecticut.