John Armstrong was chief executive of the vast King Ranch in Kingsville, Texas, and oversaw domestic operations in Mississippi, Kentucky, Pennsylvania and Florida as well as holdings in six foreign countries. He also was managing partner of the Armstrong Ranch in Kenedy County, one of three Texas counties where his family had owned ranches since 1882. He was named 1979 Man of the Year in Service to Texas Agriculture by Progressive Farmer magazine and held numerous leadership positions, including president of the Texas and Southwestern Cattle Raisers Association and president of Santa Gertrudis Breeders International.