Most employers were slow in realizing that changes in employment methods could bolster the work ethic and serve to dampen worker unrest. They were held back by their fear of raising both costs and expectations, by their emphasis on quick results, and by their skepticism about the relationship between morale and effort. Moreover, labor was cheap and abundant, and the drive system seemed an effective mode for keeping costs and expectations in line. These conditions held until 1915. But as the tightening of labor markets induced by the war created a host of new problems and intensified old ones, employers became markedly more receptive to change.