I need to find out 4 mistakes Germany made during WWI. I know one is unsrestricted submarine warfare. Another one would be the Zimmerman Note. A third one could be that they invaded Belgium. I can't think of a 4th mistake though.

http://hornherald.blogspot.com/2010/01/military-mistakes-of-world-war-1-part-2.html

http://socyberty.com/history/why-did-germany-lose-world-war-one/