There're many factors which caused the Second World War. One of them is appeasement. Appeasement is a diplomatic policy which aims to settle grievances of nations by negotiation rather than military force. It was mostly supported by the Britain prime minister at the time, Neville Chamberlain. It's said to be one of the biggest factors of the Second World War because of the following items:
1) It made Hitler stronger.
In 1935, Hitler rearmed Germany. This broke the treaty of Versailles but UK and France didn't do anything. In March7, 1936, Hitler marched in 22000 soldiers into Rhineland where was ordered to be demilitarized as the Treaty said. Once again, UK and France did nothing. Then in March11, 1938, he invaded Austria and had the anschluss (union with Austria), which broke the Treaty. Britain and France did nothing. On September29, 1938, Britain and France even agreed to give Hitler Sudetenland under the Munich Agreement.
On March15, 1939,Hitler marched into Czech, Britain and France did nothing. And this was finally the last straw. Later when in 1939 Hitler invaded Poland, Britain declared war on Germany and started the Second World War. We can see from these events that Hitler slowly gained power. These events seamed to be very little when they separate from each other. That's why UK and France allowed Hitler to take over those lands. They thought Hitler would just stop when he got this. However, they were wrong. There "little gifts" formed Hitler's great power little by little. Hitler got the army; he even got half big as Britain's navy with Britain's permit. This seemed to be the best gifts he got. Then he got Rhineland, Austria, Sudetenland and Czechoslovakia. He not only got these lands, he also got more people, more military with these pieces...