Jacob W. Roby was born in Oneida County, New York on July 9, 1824. His parents were farmers and he was educated in the common schools of the county. In 1844 he married Esther Moon of Herkimer County, New York, and five children were born of the marriage. In 1845 he became the captain of an Erie Canal boat, a position he held until 1851 when he emigrated to Wisconsin and settled on a 130-acre farm in Dodge County, Wisconsin, which he later expanded to 170 acres.
He enlisted in the Lyon Guards on September 14, 1861 with eighty-four other men from Dodge County. He was elected captain of the unit, and the Lyon Guards mustered into service as Company B of the 10th Wisconsin Volunteer Infantry on October 5, 1861. Roby participated in numerous engagements with the 10th Wisconsin including Perryville, where a bullet dented his belt buckle, and Stone River where his right arm was broken by a shell fragment. In the Battle of Chickamauga, when the commander of the regiment was mortally wounded, Roby took and retained command of the regiment, and was later commissioned Lt. Colonel of the regiment by Wisconsin Governor James Lewis.
Roby commanded the regiment in engagements at Buzzard's Roost, Lookout Mountain, Missionary Ridge, Kenesaw Mountain, Chattahoochee, and Peach Tree Creek. Peach Tree Creek was the high point of Roby's Civil War career. After Roby's horse was wounded, he dismounted and, on his own initiative, ordered his troops to a position just behind the first line of battle. After the first line collapsed he ordered a charge on the Confederate position, and the charge so surprised the enemy that when Roby ordered his troops to fire the Confederate line broke. The 10th Wisconsin suffered only one injury in the engagement. The regiment also later participated in the siege of Atlanta. On November 3, 1864 he mustered out with the rest of the regiment in Milwaukee.
After the war Roby retired to his farm and became financially successful. In 1882 he became embroiled in a lawsuit for breach of promise to marry an 18-year-old woman from Beaver Dam, Wisconsin, although he may have still been married to his first wife at the time. Later he moved to a 200-acre farm in York County, Nebraska where he married for a second time in 1900. Roby died on August 24, 1906.
