Final answer:
As the United States entered World War II, a) FDR served as the President and Commander-in-Chief, overseeing the strategic direction and supporting the Allies through initiatives like the Lend/Lease program and transforming the US economy to support the war effort.
Step-by-step explanation:
During the United States' entry into World War II, Franklin D. Roosevelt (FDR) took on the role of President and Commander-in-Chief. He was responsible for leading the country through this tumultuous period and setting the strategic vision for the war effort. However, FDR did not act as a military general in key operations; instead, he appointed skilled military leaders such as George C. Marshall as Army Chief of Staff, and Dwight D. Eisenhower to head the European Theater of Operations.
Roosevelt's efforts prior to and during the war involved diplomatic, economic, and military leadership, including initiating the Lend/Lease policies and converting the US into "the arsenal of democracy" to aid Allied forces. Ultimately, he coordinated with allied leaders including Churchill and Stalin to shape the postwar world.