Breakfast cereal he launched the Cornflakes brand, which overnight captured a national market. Soon there were forty rival manufacturers in the Battle Creek area. His brother William K. Kellogg (1860–1951) worked for him for many years until, in 1906, he broke away, bought the rights to Cornflakes, and set up the Kellogg Toasted Corn Flake Company. William Kellogg discarded the health food concept, opting for heavy advertising and commercial taste appeal. Later, his signature on every package became the company trademark. The second major innovator in the cereal industry was Charles W. Post, a salesman who was admitted to Kellogg's sanitarium as
Kellogg Switchboard & Supply Company switchboard, which became the flagship product of the new company. This switchboard offered greater flexibility and efficiency than earlier designs in handling a large telephone subscriber base at urban exchanges. Kellogg primarily supplied local independent telephone companies. In 1901, Kellogg fell seriously ill. His brother-in-law, Wallace DeWolf, proved to be a poor manager. Concerned that the company might fail, DeWolf secretly sold a majority of Kellogg's stock to Western Electric. Easily manipulated by Western Electric executives and legal advisors, DeWolf also helped Western Electric attempt to take over the country's other large telephone equipment manufacturer, Stromberg-Carlson. A bitter stockholder fight