The Japanese invasion of Manchuria, like the Italian invasion of Abyssinia, showed the League of Nations to be a paper tiger when it came to dealing with acts of illegal aggression on the international stage. In both cases, a dictatorship with dreams of empire had invaded a foreign land, and in both cases, the League had been importent in preventing these dictatorships from getting what they wanted.
In the case of the Japanese invasion of Manchuria in 1932, the League responded in the weakest possible way, by sending a fact-finding delegation to China under the leadership of Lord Lytton, a British politician and colonial administrator. The Lytton Commission, as it was called, gathered evidence and in its final report apportioned blame for the invasion on both sides. Yet the lion's share of blame was accrued to Imperial Japan, which was ordered by the League of Nations to leave Manchuria forthwith.
However, as the League lacked any military power to back up its orders, the Japanese completely ignored the ultimatum. Not only did they remain in China, but they withdrew from the League altogether, an action that would be followed by Mussolini in 1937 after the League imposed economic sanctions on Fascist Italy for its invasion of Abyssinia.