In 1912 Young published "The Military Morale of Nations and Races," a remarkably prescient study of the cultural sources of military power. He argued against the prevailing theories of the fixity of racial character, using history and social science to demonstrate that even supposedly servile or un-military races (such as Negroes and Jews) displayed martial virtues when fighting for democratic societies. Thus the key to raising an effective mass army from among a polyglot American people was to link patriotic service with fulfillment of the democratic promise of equal rights and fair play for all. Young's book was dedicated to Theodore Roosevelt, and invoked the principles of Roosevelt's "New Nationalism".