jan 5, 1931 - Manchurian Crisis
During the 1930s, many countries were going through hard depressions, Japan decided that this would be a good time to invade Manchuria, which was a resource rich area. The Chinese government went to the League Of Nations to seek help with getting Japan out. The league sent analyzed the situation for a year and then asked Japan to leave Manchuria, Japan did not listen and instead left the league. After that, the league did nothing, this is yet another example of why the League of Nations failed.
Added to timeline:
Failure of Collective Security