The additional firepower, resources, and soldiers of the U.S. helped to tip the balance of the war in favor of the Allies. Remaining Neutral. When war broke out in 1914, the United States had a policy of neutrality. many Americans volunteered for military service. Their numbers, however, were too small to build the large army needed to fight the war. At home, buying war bonds or savings stamps was probably the most common way to support the war.
