Answer:
Invasion of Manchuria and re-militarization of the German military
Step-by-step explanation:
The events that best illustrate the failure of the League of Nations are the "Invasion of Manchuria and re-militarization of the German military."
This failure above was widespread in the 1930s leading to the second world war, which began in 1939.
In 1932, Japan invaded and conquered Manchuria 1932. Also, Germany left the League of Nations in 1932 to began re-militarization of the German military under Adolf Hitler.
Another failure was the Italy invasion of Abyssinia in 1935.