When you pair up brothers and businesses, it goes two ways. It’s either the best combination or the worst. And that’s what happened between the brothers of the world’s two biggest sports companies.

Adolf and Rudolf Dassler, two German brothers, founded a shoe company in their mother’s laundry room in the 1920s. Their company took off when the Dassler shoes were seen on the feet of gold-medal-winning Olympians in the 1930s.

However, as their popularity grew, so did the rivalry between the two brothers. Their bond reached its breaking point after World War II. Although no one knows what caused the riff, it is thought to have been caused by a misunderstanding.

As the World War escalated, there’s one particular instance that many suggest was the root of the feud. According to Fortune, “when the Allies were bombing Herzogenaurach, Adi and his wife climbed into a bomb shelter already occupied by Rudi and his wife. [Adi] exclaimed, ‘The dirty bastards are back again,’ referring to the Allied forces. Rudi was convinced the remark was directed at him and his family.”

By the end of the war, the brothers had divided the company and started their own business war. Adolf, who chose the nickname Adi, branded his company Adidas, which was a combination of his first and last names; Rudolf did the same for his Ruda corporation, which he later changed to Puma. The brothers are said to have never spoken again, and their bitter dispute split Herzogenaurach, where they established opposing factories on opposite sides of the town’s river.

While there is ample room in the footwear world, even in death the two brothers couldn’t stand each other as they were buried at opposite ends of the cemetery from one another. However long after the brothers’ deaths, in September 2009, the companies set their differences aside and played a friendly game of soccer — a fitting meeting for two companies that have become independently prominent in the world of sports shoes.