Breaking the Supply Chain: How Cattlemen and Packers Cooperated to wipe out Middlemen after World War IFrom 1914 to 1921, US cattlemen launched a “war on the packers” in which they demanded large-scale federal intervention in the livestock industry. Passage of the Packers and Stockyards Act (PSA) in 1921 marked an end of the “war” and the beginning of cooperation. This research fills a gap in the literature on the livestock industry from World War I to the New Deal. Recent studies highlight this gap such as Joshua Specht’s Red Meat Republic which concludes at the turn of the century and Shane Hamilton’s Trucking Country, which begins during the New Deal. This research also builds on David Hamilton’s From New Day to New Deal, showing that the Farm Board’s attack on middlemen in the name of efficiency began much earlier and was spearheaded by actors in the private sector. Drawing on records from the American Cattlemen’s Association, the National Live Stock and Meat Board, Swift and Company, the Union Stockyards, Herbert Hoover, among others, this paper outlines how big producers and big packers cooperated to exterminate a key link in the supply chain, commission firms. Within a couple of years after passage of the PSA, which made the stockyards a public utility, cattlemen wanted to circumvent the stockyards and sell directly to the packers—placing themselves even more at the mercy of packers than they were at the stockyards. Packers also supported the creation of cooperative commission firms because they would bring them closer to producers by eliminating middlemen. Both cattlemen and packers defended their actions according to “free market” principles. Cattlemen saw that the government might place consumer interest above theirs and instead looked to packers for industry leadership.