William Cobb was born on February 6, 1809, in Gettysburg, Pennsylvania, to William Cobb and Catherine Strausbaugh. His father was an English immigrant who worked as a ship carpenter and schoolteacher. The family moved to Harrison County, Ohio, around 1816. Cobb reportedly received a “good common education” there before working as a carpenter and farmer. He married Mary Copeland on March 24, 1836, and they had at least nine children: Thomas, born on January 21, 1837; William, born around 1838; Jacob, born around 1840; Nancy, born around 1842; James, born around 1846; John, born around 1848; Christina, born around 1850; Henry, born around 1852; and Mary, born around 1855. They lived in German, Ohio, and by 1850, Cobb owned $1,300 of real estate.
The family moved to Marion, Indiana, around 1854, and Cobb purchased 240 acres of land. He belonged to the local Methodist church, and according to one writer, he “filled all the offices of his church, in which he was a prominent man. His house was the home of the itinerary Methodist preachers in the early days.” He was well-respected by his neighbors, and he served as justice of the peace for many years. By 1860, he owned $3,000 of real estate and $610 of personal property. He supported the Democratic Party, and during the Civil War, he was a “war democrat of staunch fidelity to the Union.” Three of his sons served in the Union army. By 1870, Cobb’s wealth had grown to $6,400 of real estate and $900 of personal property. He died on October 1, 1877.