In late November 1943, President Franklin Delano Roosevelt and his Joint Chiefs of Staff secretly boarded the battleship USS Iowa to attend a conference in Tehran with British Prime Minister Winston Churchill and Soviet Union leader Joseph Stalin, where the Allies would come to an agreement on a war plan to defeat Germany. Although Roosevelt s preparation at sea established the groundwork for the American position on D-Day, it was in the heated and electrifying debates that followed in Tehran and only through those intense debates that a deal was ultimately struck.