Norway April though June 1940.
Rather than me paraphrasing lets read what this author has to say:
The German Decision To Invade Norway and Denmark
by Earl F. ZiemkeThe German invasion of Norway was a dramatically daring military operation. The decision to embark on the venture was made by Adolf Hitler as Chief of State and also (since December 1938) as Commander in Chief of the Armed Forces of the German Reich. He arrived at it over a period of six months during which the proposal was debated at length in the highest echelons of the German Armed Forces. Hitler’s own attitude shifted during that time from lukewarmness verging on indifference to determination. Since the war the decision has been both praised and condemned; here it is presented as an example of decision-making in a developing situation. 
Even though the occupation of Norway and Denmark had no significant effect on the outcome of the war, it established a milestone in the history of warfare by demonstrating the effective reach of modern military forces. Although lacking the resources to capitalize on it, the Germans had made a move of potential value to them in the development of a global strategy. It confronted the United States as well as Great Britain with a strategic threat. It brought Germany, theoretically at least, into a position to strike outward from the mainland of Europe toward Iceland, Greenland, and possibly the North American continent.
WelI I strongly doubt the feasibility of a North American effort. But you get the idea. The securing of the Northern approaches was smart, and in the end not expensive for the Germans.
Our look at this part of the Chronological walk through WWII is going to be brief. Primarily due to a lack of solid titles that are reasonably priced and sized. The Command Magazine product seemed like a solid choice given especially that it focused upon the post landing efforts through the beginning of Fall Gelb in May 1940.
Full AAR to come.
- Winter War [Chrono] (meshtime.com)