The German invasion of Denmark.
The German invasion of Denmark was the fighting that followed the German army crossing the Danish border on 9 April 1940 by land, sea and air. Lasting approximately six hours, the German ground campaign against Denmark was one of the shortest military operations of the Second World War.
Denmark was a peaceful country that had just agriculture economy, not had industrial growth. They didn't invest on Army's modernisation. They had to fight against German tanks with the bicycle infantries.
The king and the government continued their life as before but there was a growing secret resistance inside people. In 1943, when Germans wanted the jewish people to surrender, resistants took a big risk and sent %99 of them to Sweden.
In 1945, after Hitler's surrender, 2000 german soldiers were elected to clear the german mine fields in Denmark. Half of those young soldiers were died or seriously injured because of that inhumanity.