Douglas was born on April 23, 1813 in Brandon, Vermont. He was raised in Jacksonville, Illinois. He was married to Martha Martin from 1847 until her death in 1853. They had three children. Then he was married to Adele Cutts from 1856 until his death in 1861. They had one child. Douglas died from pneumonia caused by Typhoid fever in Chicago, Illinois on June 3, 1861, aged 48.