On this day in 1941, the United States Congress amends the Neutrality Act of 1935 to allow American merchant ships access to war zones, thereby putting U.S. vessels in the line of fire.
In anticipation of another European war, and in pursuit of an isolationist foreign policy, Congress passed the Neutrality Act in August 1935, forbidding the sale of munitions by U.S. firms to any and all belligerents in any future war. This was a not-so-subtle signal to all governments and private industries, domestic and foreign, that the United States would play no part in foreign wars. Less than two years later, a second Neutrality Act was passed, forbidding the export of arms to either side in the Spanish Civil War.
The original 1935 act was made even more restrictive in May 1937, forbidding not only arms and loans to warring nations, but giving the president of the United States the authority to forbid Americans from traveling on ships of any warring nation, to forbid any U.S. ship from carrying U.S. goods, even nonmilitary, to a belligerent, and to demand that a belligerent nation pay for U.S. nonmilitary goods before shipment--a "cash and carry" plan.
But such notions of strict neutrality changed quickly once World War II began. The first amendment to the act came as early as September 1939; President Roosevelt, never happy with the extreme nature of the act, fought with Congress to revise it, allowing for the sale of munitions to those nations under siege by Nazi Germany. After heated debate in a special session, Congress finally passed legislation permitting such sales. Addressing the prospect of direct U.S. intervention in the war, President Roosevelt proclaimed, also in September 1939, that U.S. territorial waters were a neutral zone, and any hostile power that used those waters for the prosecution of the war would be considered "unfriendly" and "offensive."
Finally, when the U.S. destroyer Reuben James was sunk by a German sub in October 1941, the Neutrality Act was destined for the dustbin of history. By November, not only would merchant ships be allowed to arm themselves for self-defense, but they would also be allowed to enter European territorial waters. America would no longer stand aloof from the hostilities.
Taken from: http://www.history.com/this-day-in-history/congress-revises-the-neutrality-act [13.11.2014]