To a larger extent, the failure of the collective security paved the way for the Second World War (WWII). The aim of making attempts of collective security was to maintain world peace and avoid war, but due to lack of support from the countries, disagreement among powers and lack of enforcement power, the three attempts of collective security (i.e. The League of Nations, peace treaties and disarmament conferences) failed. The failure of the collective security increased the hostility among powers and encouraged Hitler and Mussolini to start foreign expansion, which posed a threat to the whole world and led to the outbreak of WWII.
However, there were other factors which brought about WWII .To a little extent, the Paris Peace Settlement paved the way for WWII. Since Italy failed to get what it thought it deserved in the Paris Peace Settlement, the Italians were very discontented. Therefore, Mussolini introduced totalitarianism, and started his foreign expansion by invading Abyssinia and Albania in 1935 and 1939 respectively.
Meanwhile, The Paris Peace Settlement also aroused the resentment and a strong desire for revenge among the Germans as they were suffered from the harsh treaty terms in the Paris Peace Settlement. Therefore, they supported the Nazi Party for revenge. As soon as the Nazi Party was in power, it rearmed Germany, sought to repudiate the Treaty of Versailles and planned for foreign expansion. For example, Germany invaded Poland and Czechoslovakia in 1939.
To a little extent, the Great Depression paved the way for WWII. The Great Depression had hit the USA, Britain and France badly. As they needed time to concentrate on rebuilding their own economies, they couldn’t stop the aggression of Hitler at the same time. The Great Depression had provided a favourable condition for Hitler to raise his Nazi party, which allowed him to form the Berlin-Rome-Tokyo Axis In 1937 and declared Anschluss (union with Austria) and occupied Austria in 1938. The aggression of Hitler increased the hostility among powers, finally led to WWII.
To a little extent, the appeasement policy also paved the way to WWII. The aim of adopting appeasement policy was to satisfy the ambitions of an aggressor so as to avoid war. Facing the expansion of the Axis Powers, Britain and France responded with appeasement but this only encouraged the ambitions of the aggressors and brought the world closer to war.
To a little extent, the aggression of Japan paved the way for WWII. In the late 1920s, militarism rose up in Japan. On 18 September 1931, Japan invaded Manchuria. The Second Sino-Japanese War begun in 1937. The aggression of Japan towards China had alarmed the whole world, which finally led to WWII.
From the above analysis, there are 5 main factors paving the way for WWII, viz. the Paris Peace Settlement, the failure of collective security, the Great Depression, the appeasement policy and the aggression of Japan. I believe that to a larger extent, the failure of collective security paved the way for WWII. The main aim of carrying out collective security was to maintain world peace and avoid war.
The Paris Peace Settlement was less important in paving the way for WWII. Even the Paris Peace Settlement aroused the discontentment of the Italians and the Germans, which brought out to the rise of Mussolini and Hitler; if the other powers were willing to support the collective security attempts and avoided causing disagreement, Mussolini and Hitler would not succeed in foreign expansion. For example, The League could not prevent Italy from seizing Abyssinia in 1935-36 and Albania in 1935. When Hitler violated the Treaty of Versailles by rearming Germany and remilitarizing the Rhineland, the League could not stop him. As a result, Germany went on to annex Austria and the Sudetenland in 1938. The above events could be certainly prevented if the League could be more powerful.
The Great Depression was less important in leading WWII as it only hit the economies of some major powers. Although the Great Depression would act as an obstacle for Europe to carry out international cooperation, it was not so influential that it would cause WWII immediately. Only with the failure of the collective security, the powers would mistrust one another and they could not stop the aggression of the Axis powers.
The appeasement policy was less important in paving the way for WWII. Even the appeasement policy failed to satisfy Hitler and encouraged his aggression, if the collective security could work out successfully, the aggression of Hitler could be controlled. The collective security had a responsibility to stop the ambitions of the aggressive powers, but as they failed at all, the aggressive powers continued their foreign expansion.
Although Japan had carried out a massive attack towards China, it was not an immediate cause of WWII as only with the aggression of Japan, it was not such influential that it could cause a world war. Due to the failure of collective security, Japan became more aggressive and alarmed the whole world. If the collective security could maintain peace, the aggression of Japan could be under control. For example, after the Manchurian Crisis, The League of Nations sent the Lytton Commission to investigate the crisis. It condemned the aggression of Japan and ordered Japan to withdraw its troops. However, Japan simply ignored and continued her aggression. If the Lytton Commission could be more effective, the aggression of Japan could be prevented
To conclude, to a little extent, the Paris Peace Settlement paved a way for WWII and I believe that to a larger extent, the failure of Collective security paved a way for WWII.