Fordson-Putilovets tractors (Фордзон-путиловец). During the 1920s, the Soviet versions had a reputation for insufficient quality. Much of this was because the metallurgy and heat treatment were wrong. For example, no matter how perfectly one machines a shaft or gear, it will fail early if the hardness is wrong. As Soviet industrialization progressed in the 1930s, the worst of the quality problems were solved. By mid-1918, more than 6,000 Fordson tractors, all U.S.-built, were in use in Britain, Canada, and the United States. After World War I ended, production began in Cork, Ireland, in parallel with U.S. production. Fordson tractors quickly shaped the U.S. tractor market, and held over 70% of the market in earlier years. Henry Ford had a power struggle with Ford Motor Company's shareholders (including the Dodge Brothers, Horace and John Dodge) that culminated in 1919. He resigned from Ford Motor Company with the threat (fully realizable) to treat Henry Ford & Son Inc as his new enterprise for all of his future cars, trucks, and tractors (he would begin with all-new designs), which would turn Ford Motor Company into a mere badly led competitor, destroying its stock's value. This maneuver worked; Henry Ford bought out all the minority shareholders of Ford Motor Company in 1919, and then consolidated ownership in the Ford family: fifty-five percent in his name, forty-two percent in son Edsel's name and the remaining three percent in wife Clara's name. He merged Henry Ford & Son into the Ford Motor Company in 1920. Annual production reached 36,781 in 1921. The Fordson had established a firm foothold on U.S. farms. In February 1922, after sales had suffered from the depression of 1920–1921 and with stiffer competition from International Harvester, John Deere, J.I. Case, Allis-Chalmers, and others, Ford decided to reduce the price of the Model F from $625 to $395. This sparked a price war in the tractor industry known as the "tractor wars". To compensate for the lower price, Ford had to cut costs and strive for larger-volume production. Meanwhile, in Ireland, the Irish War of Independence occurred. Production at Cork never flourished during this first period, although a few thousand tractors a year were built. Ford ended production at Cork in 1922 and shipped the factory's equipment back to the U.S. in 1923. (It would return some years later, as described below.) By 1925, Ford had built its 500,000th Fordson tractor. Annual production