Final answer:
FDR's death was a crucial turning point in post-war agreements, occurring just before the end of WWII and impacting the shaping of the post-war world.
Step-by-step explanation:
True, FDR's death was indeed a turning point in post-war agreements. As a dominant figure in world politics during World War II, Franklin Delano Roosevelt (FDR) significantly influenced the formation of post-war structures and policies. His death in April 1945 came just before the end of the war in Europe and months prior to the conclusion of World War II in September with Japan's surrender. FDR had been a leading voice in the negotiations and strategy to ensure a sustainable post-war peace, and his death meant that the job of fully realizing his vision fell to his successor, Harry S. Truman. This transition came at a critical point when major decisions about the post-war world needed to be made - such as the formation of the United Nations, the approach to the rebuilding of Europe, and the handling of relations with the Soviet Union - which would influence international dynamics for decades to come.