In 1919, John Deere entered the harvester business, and International Harvester's reply to their new competition was to purchase P&O Plowing of Canton, Illinois, and the Chattanooga Plowing company of Chattanooga, Tennessee. Henry Ford also entered the tractor business with his Fordson Tractor produced at the massive Rouge River plant. An economic downturn during the early 1920s dampened tractor sales; price-cutting to stimulate demand sparked a price war in the tractor industry (called the tractor war). Ford, with a massive advantage in manufacturing capacity and distribution, had the upper hand, producing an estimated 73 percent of all American tractors, with IHC in a far away second place at nine percent, and several other companies sharing the rest of the percentages. In 1923, the IHC Farmall entered the agricultural industry, and Ford's stranglehold began to slip. That same year also, the 100,000th thresher machine produced by Case made its way out of the assembly line, marking an important milestone for the Case company.