William Jacob was born 27 March 1815, in Hampshire, England.  He arrived in South Australia on the Rapid (ship) in 1836 as one of Colonel William Light's surveyors. He married Mary Elizabeth nee Bagot 31 August 1842 at Koonunga, South Australia.

His younger brother John came to South Australia in 1838 on the William (ship).  Sometime after he joined with his brother William at Moorooroo in the Barossa. William also established a vineyard at Moorooroo. After being involved in other pastoral runs in the mid north the brothers settled at Paralana in the Gammon Ranges. Paralana is recorded as comprising 582 square miles of country: at its most profitable period it was stocked with 7000 cattle. This great herd was nearly entirely wiped out in the drought of the 1860s. 

The Jacob brothers have given their name to one of the great wine regions of Australia: Jacobs Creek. Jacob's Creek was named by William Light, after his surveying assistant, William Jacob who subsequently settled on the banks of the Creek with his brother John at Moorooroo.

William Jacob died at Moorooroo 14 July 1902, age 88.