A year before the Japanese attack at Pearl Harbor brought the United States into the war, President Franklin Roosevelt went on the radio to address the nation and make the case for an open-ended loan to Britain. He tied the fates of the two nations together, suggesting what was best for the defense of Britain, who was in fourth month of an air war with Gemany, and gave the metaphor of lending a water hose to a neighbor whose house is on fire. As long as the supplies are returned or replaced, he said, there should be no qualms about lending them to help. This was the foundational philosophy behind the Lend-Lease Act.

On this day, March 11, President Franklin D. Roosevelt signed into law the Lend-Lease Act that authorized the transfer, sale and exchange of material to any country fighting the Axis Powers. It was not a full declaration of American entry into the war, but did mark the first time the U.S. formally broke its neutrality.

Although the bulk of of the Lend-Lease materiel went to Britain, there was arguably no place where it made a bigger impact than in Russia. The U.S. shipped over to Russia planes, armored vehicles, and various supplies, but it was the delivery of entire manufacturing facilities that enabled the half-industrialized country to start churning out enough weapons and ammunition to beat back the German war machine.