John B. Warren was the first man to display a particular interest for business, and a good business makes for the progress and stability of any town.  Warren owned a flour and grist mill from 1837-65, a general store at Four Corners, and built a brewery. In 1865, Warren had misfortune fall upon him due to a price slump at the end of the American Civil War (1861-5). When this happened, Warren was blamed by the farmers who were also affected by the decline in prices, with this, Warren was financially ruined. This was the beginning of the end for the Warren family in Oshawa. John Warren eventually died in 1879.