Congress passed a series of four neutrality acts in the 1930s that were designed to keep the United States out of World War II. They reflected the isolationist mood of the country and the general conclusions of the Nye Committee that it was the self-interest of bankers and arms merchants that had propelled the United States into World War I. The neutrality legislation became a constant source of political tension between Congress and President Franklin Roosevelt, who opposed many of its features and, on occasion, actively worked to circumvent them. Critics of the neutrality legislation argued that it would not accomplish its goal of keeping the United States out of World War II. It was backward-looking (fixating on the forces and events that led to U.S. involvement in World War I) and not attuned to the political-military realities of Europe.
Congressional debate over a neutrality act began in 1935 against the backdrop of the Chaco War between Bolivia and Paraguay and the widely anticipated Italian offensive against Ethiopia. Roosevelt endorsed the concept of an arms embargo but favored legislation that would grant him the freedom to prohibit weapons sales only to the aggressor. Congress refused and passed the first Neutrality Act, which barred weapons sales to all participants. Opponents of Roosevelt's plan asserted that the act of selling weapons to the “victim” of aggression would involve the United States in the conflict and would be a violation of the principle of neutrality. The act also warned Americans that they traveled on belligerent vessels at their own risk. This warning was a reprise of the lengthy debate that occurred on the eve of World War I when the Wilson administration debated how to respond to German submarine warfare against British vessels carrying American passengers. The death of Americans in these attacks became one of the justifications given by Woodrow Wilson for declaring war on Germany.
Roosevelt publicly objected to the act's “inflexible provisions” and warned that the Neutrality Act might drag the United States into war. Nonetheless, he signed it into law on August 31, 1935. In October 1935 Italy invaded Ethiopia. Roosevelt acted quickly to invoke the Neutrality Act and stop arms shipments to either side. Consistent with its isolationist impulse, the United States refused to join with the League of Nations in imposing an embargo on Italy for being the aggressor. Instead, Roosevelt and Secretary of State Cordell Hull called for Americans to undertake a “moral embargo” against Italy and suspend trade in oil, steel, and other vital goods.
In 1936 Congress passed the second Neutrality Act. The first act was set to expire, and the 1936 act extended its provisions for an additional year. The 1936 Neutrality Act also added new provisions. Under the terms of the first act, the president could at his direction extend the arms embargo to any state entering the conflict. The 1936 legislation required him to do so. Second, the administration was not barred from making loans to belligerents. This new clause incorporated the logic of the Nye Committee's report.
The intent of the 1936 Neutrality Act faced a difficult test in the 1936 Spanish civil war that pitted General Francisco Franco against the Spanish Republican government. Germany and Italy supported Franco. France, Great Britain, and the Soviet Union supported the Republicans. Roosevelt sought to follow the lead of France and Great Britain and deny weapons to either side. The problem was that the neutrality legislation did not authorize him to act in cases of civil wars. Moreover, traditional U.S. policy toward Latin America had been to sell weapons to governments involved in a civil war while denying them to the insurgents. With voluntary controls not working, Roosevelt asked Congress to amend the 1936 act to include civil wars. It did so through a joint resolution passed in January 1937.
Congress took up the matter of neutrality legislation again that spring. The 1936 act was set to expire in May. The third Neutrality Act passed by a joint resolution on April 30, 1937. The 1937 Neutrality Act was of indefinite duration, and its content represented a compromise among competing factions that disagreed over the wisdom of the neutrality legislation as it had evolved but were united in their desire to keep the United States out of war. The amount of discretionary power to be given to the president again was a major point of debate as Roosevelt increasingly sought ways to involve the United States in collective security undertakings. The new legislation made travel on belligerent ships through “danger zones” unlawful. It permitted belligerents to buy other supplies from the United States provided they paid in cash and transported these goods in their own vessels. The cash-and-carry provisions of the 1937 act were limited to two years. The ban on loans was continued, and U.S. merchant ships trading with belligerents were not allowed to arm themselves.
The continued march of events toward war in Europe led Roosevelt to call for repeal of the neutrality legislation in his January 1939 address to Congress. He argued that attempts to deliberately legislate neutrality had failed to protect U.S. security interests: “Our neutrality laws may operate unevenly and unfairly … the instinct of self-preservation should warn us that we ought not to let that happen anymore.” He followed this address for large increases in defense expenditures. On May 1, the cash-and-carry provisions of the 1937 act expired, and Roosevelt asked Senate leaders to secure the approval of Congress to repeal the arms embargo so that weapons could be shipped to Great Britain and France. Isolationist sentiment remained strong, and in August Congress adjourned without taking action.
Adolf Hitler's troops poured into Poland on September 1, 1939. Two days later Great Britain and France declared war on Germany. Two weeks after the invasion Roosevelt called Congress into special session and asked for the revision of the neutrality legislation. Six weeks of heated debate led to the passage of the fourth Neutrality Act on a near perfect party-line vote, with only a handful of Republicans voting for the new act. The 1939 act permitted the president to provide short-term credits of 90 days to belligerents. It also repealed the arms embargo and allowed the Allies to purchase weapons on a cash-and-carry basis. In a concession to isolationists it forbade any U.S. ship from entering into areas designated as combat zones by the president. Roosevelt signed the act into law on November 4, 1939.
Commentators have referred to these neutrality acts as representing an attempt at “storm cellar” neutrality. From this point forward, Roosevelt led the United States on a path away from traditional neutrality to one of nonbelligerency. The United States was actively aiding Britain and France, but its participation stopped short of declared war. With Great Britain strapped for cash, Roosevelt first agreed to swap 50 American destroyers for the right to establish navy and air bases on British territory in the Western Hemisphere. This was followed by the Lend-Lease Act of 1941, which circumvented the cash portion of the cash-and-carry section of the Neutrality Act. Finally, in November 1941 Roosevelt asked Congress to repeal the Neutrality Act so as to allow the arming of U.S. merchant vessels and the abolition of combat areas so that U.S. ships could carry Lend-Lease goods directly to the Allies. It did so by a vote of 50-37 in the Senate and 212-194 in the House.