"The National Insurance Act of 1923 forced many clubs to cease direct employment of caddies. Improved course management and greens keeping forced smaller and weaker clubs to cease operations as players gravitated to the best courses. The expansion of motor car use also affected the rail companies. The line through Ayrshire to Turnberry ceased operation in 1930, for example. The Great Depression of the 1930s followed by World War II, and austerity measures of the 1950s had a negative impact on golf, as economic hard times and war limited the numbers who could play. War measures meant that lesser-used rail lines and old golf clubs were collected to add to steel needed for the war effort. Many clubhouses were used by the military, and gasoline rationing meant that clubs could not cut fairways of greens as frequently as they would like. Even the 9-hole course that Andrew Carnegie had constructed as Skibo Castle near Dornoch was used for food production during the war. Other courses suffered similar fates. Some courses like St. Andrews and Dunbar survived by using the courses for sheep or cattle grazing. Turnberry's course was temporarily converted to an air field. Consequently, British golfing performances at the top level also suffered. There was a brief revival in the late 1930s and again in the 1980s, which coincided with improved success by British and Irish golfers in tournament play."