japan
They invaded the Chinese province of manchuria in 1931 That would have been the League of Nations, as UN didn't exist until 1945.
The League did absolutely nothing about it. They figured they should leave well enough alone because it had no effect on them, so why bother?
Japan decided to invade Manchuria the day after the Mukden incident, in 1931. However, the entire state of Manchuria was not conquered until 1932, so the answer to the question is 1932.
Disputes and crises in the contemporary world threaten international peace.
In 1931 Japan invaded Manchuria. To cover up their invasion, the Japanese imposed a new "puppet" government (a government controlled by them) that was meant to approve their presence in Manchuria. The name of Manchuria changed to Manchukuo and therefore so did the name of the government. The League of Nations sent a commission to investigate whether or not the Manchurians really wanted the Japanese there called the Lytton Commission. They determined that, in fact, the Japanese were not welcome in Manchuria. This basically eventually lead to the Japanese withdrawing from the League of Nations.
America was never a member at allGermany wasn't allowed to be a member due to the treaty of Versailles however they joined eventually but withdrew with the Rise of HitlerThe USSR was not a member but did eventually join. It also withdrew.Italy and Japan were members but withdrew following invasions of Abyssinia and Manchuria respectively.
There are almost too many to count. The replacement of democratic type governments by totalitarian stares. The Spanish Civil War. The collapse of the Leauge of Nations. Invasions of Manchuria, Ethiopia, Austria, and Czechoslovakia. There are many others.
The first example is the Japanese invasion of Manchuria. The League of Nations disapproved but had no means to stop the invasion. Mussolini then invaded Ethiopia in 1935, and the League of Nations was unable to take action against him. Finally, in 1936, Hitler began to remilitarize Germany, and there was no reaction from the League of Nations.
After the condemnation, Italy and Japan withdrew from the League of Nations.
Germany
Other nations began to test its power and Germany also withrdrew