Major U.S. Policy Changes

        Between September 3, 1939, when WWII began, and December 7, 1941, when Japan bombed Pearl Harbor, the United States gradually abandoned its policy of strict neutrality and moved to all-out war on the Allied side. The major events involved are outlined in the following sections.
        Events on this page are linked to both the historical timeline  and the diplomatic timeline  in order to set these developments in the full context of events in the rest of the world.

Cash and Carry

Shortly after war broke out in Europe, President Roosevelt asked Congress to repeal the arms embargo embodied in the Neutrality Act of 1937 so that arms could be sold to Britain and France. FDR Asks for Loosening of Arms Embargo  In November, the Neutrality Act of 1939 was passed in order to Neutrality Act of 1939 Neutrality Act of 1939 permit belligerents to purchase materials of war on a cash and carry basis.  However, while loosening U.S. isolationism in one respect, it banned American merchant ships from traveling in war zones, which constituted a strict municipal limitation on the traditional right of neutrals to free navigation of the seas.  Cash and Carry did aid Britain and France who, because their financial resources and control of the seas, were able to buy war materials in the United States as long as the goods never traveled on U.S. ships.  Though Cash and Carry marked a definite shift from pure isolation to pro-Allied neutrality, it actively sought to compensate for this by requiring that the U.S. relinquish some of its rights as neutrals.

Beginning of Active Aid to the Allies

The quick and unexpected fall of France to the Nazis in 1940 Fall of Paris Fall of Paris shocked most Americans out of their complacent attitude.  President Roosevelt determined that national security demanded that Germany not be permitted to become the dominate power in Europe and, along with the American public, became convinced tha the U.S. must privide the Allies with "all-out aid short of war."  Several significant developments in 1940 and 1941 indicated growing concern and increasing involvement.

The Lend-Lease Act (March, 1941) Lend-Least Act Lend-Lease Approved

By December, 1940, public opinion polls showed that 60% of the American people favored helping Britain even if it led to war.  In March, 1941, therefore, while Britain alone withstood the Nazi onslaught, the United States Congress passed the Lend-Lease Act.  The Lend-Lease Act empowered the president to "lend, lease, or exchange" war materials with nations whose struggle against aggression was considered necessary to American security.  It made the United States the "arsenal of democracy," and it became a factor in the final victory of the Allies.

Undeclared Naval War With Germany

The Lend-Lease Act led to a state of undeclared naval warfare with Germany. Believed First Act of War Between U.S. and Germany
Mastering History:P.L.Grossier;Oxford Book Co.;1st. Ed.;1974

Summary based on the following webpage.