Starting in the 1960s, Fortress expanded beyond Southern California and by the 1970s had showrooms in San Francsico, Texas, Chicago, Florida, and was selling desks internationally. The products were usually specified by the design community because of the contemporary design of the desks and files and the attention to detail in the upholstered seating. In 1979 a fire destroyed the Irwindale factory where the desks and files were manufactured.
A decision was made by the owners to abandon the desk and file business and concentrate on seating. The product line continued to develop and at the request of Kaiser Permanente Fortress started to develop waiting room furniture and recliners for dialysis and chemotherapy procedures.
The company was sold in 1992 to the National Sales Manager, Donald Wolper. In 1999 Neal Parsons of Home Theater Resources commissioned Fortress to build a home theater chair he had designed and Fortress entered a new phase in evolution.