Ross served in Captain Constant's Company, Colonel Neale's Detachment, of the Illinois Mounted Riflemen in the Winnebago Indian Disturbances of 1827.

[6] He also saw service in the Black Hawk War of 1832 as a sergeant in Bogart's Brigade, Captain John Sain's Company, Odd Battalion of Mounted Rangers.

In an address to the U. S. House of Representatives in 1864, Ross invoked the late Senator Douglas and called for a cessation of the conflict through "mutual concessions and a fair and just compromise.

[17] Nevertheless, Ross' position reflected that of many of his fellow citizens of Fulton County, as evidenced by the fact that he was twice re-elected to Congress.

[15] During the Reconstruction Era following the Civil War, Congressman Ross generally tended to favor the moderate position taken by President Andrew Johnson, and he opposed the policies that were promoted by the Radical Republicans.

He also expressed continuing regret that the views of Senators Crittenden and Douglas advocating compromise had not prevailed during the runup to the Civil War.

[19] Ross argued that the U.S. Government had no constitutional right to impose military rule on the southern states that had participated in the Confederacy.

Although he was considered by some individuals as a possible candidate for the office of Vice President of the United States in 1868,[20] Ross retired from politics after his service as a congressman in order to manage his considerable real estate holdings in Lewistown and Havana and to pursue his business interests.

In 1878, Ross was involved in the incorporation of the Fulton County Narrow-Gauge Railroad Company,[21] which ultimately built a line between Galesburg and West Havana, Illinois.

[23] Lewis Ross died in Lewistown, Illinois, on October 29, 1895, as a consequence of a burst blood vessel in his head.