The campaign took place against a background dominated by war — the Mexican Revolution and World War I. Although officially neutral in the European conflict, public opinion in the United States favored the Allied forces led by Great Britain and France against the German Empire and Austria-Hungary, due to the harsh treatment of civilians by the German Army and the militaristic character of the German and Austrian monarchies. Despite their sympathy for the Allied forces, most American voters wanted to avoid involvement in the war and preferred to continue a policy of neutrality. Wilson's campaign used the popular slogans "He kept us out of war." and "America First" to appeal to those voters who wanted to avoid a war in Europe or with Mexico. Hughes criticized Wilson for not taking the "necessary preparations" to face a conflict.