After the American Civil War, Brown joined the Republican Party for a time, and was appointed as chief justice of the Supreme Court of Georgia from 1865 to 1870.

Later he rejoined the Democrats, became president of the Western and Atlantic Railroad and began to amass great wealth; he was estimated to be a millionaire by 1880.

During this time he was part of the Bourbon Triumvirate, alongside fellow prominent Georgia politicians John Brown Gordon and Alfred H. Colquitt.

With the help of his younger brother James and their father's plow horse, Brown drove a yoke of oxen on a 125-mile trek to an academy near Anderson, South Carolina.

A friendship developed between the men, and Lewis loaned Brown money to continue his legal education.

[6] Brown joined the Democratic Party and was soon elected to the Georgia state senate in 1849 from the developing Etowah River valley.

He supported free public education for poor white children, believing that it was key to development of the state.

He asked the state legislature to divert a portion of profits from the state-owned railroad, the Western & Atlantic, to help fund the schools.

The Western and Atlantic Railroad was mismanaged, and unable to produce the income Brown required to fund his public education proposal.

The railroad, said to be in "dire financial straits", required the same strict economic controls Lewis had practiced in his private businesses.

[10] Brown easily won re-election in 1859 when he defeated a young Warren Akin Sr. (who was just beginning his political career) by a margin of 60%-40%.

If we fail to resist now, we will never again have the strength to resist.Once the Confederacy was established,[15] Brown, a states' rights advocate, spoke out against expansion of the Confederate central government's powers.

Brown tried to stop Colonel Francis Bartow from taking Georgia troops "out of the state" to the First Battle of Bull Run.

In time, other Confederate governors followed Brown's example, undermining the war effort and sapping the Confederacy of vital resources.

Brown wrote to Lewis, saying: "I did not deserve this at your hands, and I confess I felt it keenly...I do not attribute improper motives, but only say the coincidence was an unfortunate one for me".

On the route from Atlanta to Savannah the left wing of Sherman's army entered the city of Milledgeville, then Georgia's state capital.

As U.S. troops closed in on the city, and with the fall of the capital imminent, Governor Brown ordered Quartermaster General Ira Roe Foster to remove the state records.

Brown, thinking first of the valuable and perishable State property, ordered Gen. Ira Foster, Georgia's quartermaster general (who was always prompt and efficient), to secure its removal.

When the Governor saw the condition of affairs, he went to the penitentiary, had the convicts drawn up in a line, and made them a short speech; he appealed to their patriotic pride and offered pardon to each one who would help remove the State property and then enlist for the defense of Georgia.

They were ordered to report for duty to Gen. Wayne, who was commanding a small battalion of militia at Milledgeville and also the Georgia cadets from the Military Institute at Marietta.

He supported President Andrew Johnson's Reconstruction policies, joining the Republican Party for a time.

Soon after his election to the Senate, Brown became the first Democratic Party official in Georgia to support public education for all white children.

[29] It was expanded during the post-Reconstruction era, when the Democratic-dominated state legislature passed new laws criminalizing a range of behavior.

They reported that the convict laborers were "in the very worst condition ... actually being starved and have not sufficient clothing ... treated with great cruelty.