Lyman was the youngest child of George W. and Phebe Dennis. He grew up on the farm in DeKalb County, Illinois.

He enlisted in the Civil War when 17 years of age in the 8th Illinois Cavalry, Co. B - He was mustered out September 28, 1864 at Chicago, Illinois. He saw much combat service and was taken prisoner at Bell Island. Mustered in the 18th of September 1861 at St. Charles, Illinois. War records say he was enrolled at Sycamore, Illinois August 27, 1861 as a private. He was 5 feet 8 1/2 inches in Height. Hair was brown, eyes gray and he had a dark complexion. He was a farmer.

Lyman and his wife moved to Labette County, Kansas about 1870 and homesteaded a claim seven miles east of Liberty, Kansas. Before his daughter Letice was born in 1886, the parents traded their farm in Altamont, Kansas for a furniture store in Oswego, Illinois but later moved back to Labette County, Kansas where he died.

"Altamont Journal"
Altamont Kansas Thursday, August 15, 1918

Death of Lyman Dennis

Lyman Dennis one of the most highly respected men in Labette county died at his home in Altamont, Kansas, August 14, 1918. The funeral was held at the M.E. church at 10 this morning conducted by the former pastor, H. W. Todd of Arcadia, and the remains were consigned to the grave in the Altamont cemetery.
Lyman Dennis was born in Wyoming county, New York, Feb. 22, 1843 and passed away at his home in Altamont, Kansas, August 14, 1918, aged 75 years, 5 months and 23 days. He was united in marriage to Louise Parker July 18, 1866. To this union seven children were born, two boys and five girls. The wife and three children survive, one daughter and two sons. Four daughters precede him.
The deceased was a veteran of the Civil War and the old veterans of the community give him credit of having the best soldier record among the boys who remain. He enlisted at the age of 18 and served his country four long years.
He united with the M. E. church at an early age and lived his religion at home and wherever he happened to be. He will be greatly missed and sadly missed by his immediate friends as well as many friends for the home tie was a great factor in his family.
The deceased was one of the earlier settlers of Altamont and no one ever lived here who enjoyed the confidence and the respect among his fellow men more than Mr. Dennis.