Germany and the Soviet Union invasion of Poland in Sept. 1939
France
Already before the start of World War 1 most European countries had compulsory military service.
Switzerland
France
Italy
Poland was the first Allied country invaded & defeated by Germany in WW2.
Germany and Italy
The tiny European island country of Malta - after World War II.
France
The increased investment in European militaries
Switzerland
Yes World War 1 is a European War.