Did Western Democracies Stop the Aggression of France, Japan, and Germany in WWII?

No. Western democracies (primarily the U.S., U.K., Soviet Union, and others) fought against the Axis powers—Germany, Italy, and Japan—to halt their aggression. France was an Allied power (though it fell in 1940). The war ended in 1945 with Axis defeat and the founding of the United Nations to prevent future conflicts.