Few business rivalries have had a greater impact on global sports than the bitter split between brothers Adolf Dassler, better known as Adi, and Rudolf Dassler. In the 1920s, the brothers built a successful shoe business called the Dassler Brothers Shoe Factory, producing innovative athletic footwear that gained worldwide attention after American sprinter Jesse Owens won four gold medals wearing their shoes at the 1936 Berlin Olympics.

After World War II, however, the brothers’ relationship completely collapsed. While the exact cause remains a mystery, historians point to a mixture of family tensions, political disagreements, and business disputes. The feud became so intense that they stopped speaking altogether.

In 1948, Adi founded Adidas, combining his nickname and surname (“Adi” + “Das”), while Rudolf established Puma the following year. Both companies remained headquartered in Herzogenaurach, turning the small town into the center of one of the world’s fiercest corporate rivalries. Residents were said to look at each other’s shoes before deciding where to shop or even whom to socialize with, earning Herzogenaurach the nickname “the town of bent necks.”

Today, Adidas and Puma are global brands worth tens of billions of dollars, sponsoring the world’s biggest athletes, clubs, and sporting events. What began as a family dispute ultimately reshaped the sportswear industry and created two of the most recognizable brands on Earth.