The Anti-Federalists did not agree with the Constitution and the Federalist system because they believed that a strong central government had the potential to create an absolute government which was the reason they got independence from Britain. So, they imposed the creation of a Bill of Rights to ratify the Constitution, the Bill of Rights was a way of protecting individual rights from a President that had too many powers.
The previous constitution, called the Articles of Confederation, gave state governments more authority. Led by Patrick Henry of Virginia, Anti-Federalists worried, among other things, that the position of president, then a novelty, might evolve into a monarchy
After the many failures of the League of Nations, the countries involved knew they had to make a stronger league that would better protect them from war and world conflict. I believe this happened in 1945, though, not 1943.
