WW1 during stage 1.

On August 4, 1914 Germany invaded neutral Belgium. The First World War had become a fact.
It was unclear at the time if Germany would also invade the Netherlands. Maastricht gave shelter in the caves of the St. Pietersberg, in the factory halls of the Sphinx and in the Augustinian Church to about 15,000 Belgians in the first weeks of the 1st World War.
Almost every week in those days the Dutch Red Cross traversed the Belgium border to pick up all the wounded soldiers .
In January 1915, the German government decided to combat the unwanted border traffic with the Netherlands and an approximately 4 meter high border barrier was built and reinforced by 2,000 volt electrical wires.
From 1916, the shortage of goods became general in the Netherlands as a result of the warfare and the blockades on sea and roads.
There is only one monument in Maastricht that commemorates the 1st World War. That is a French national monument of gratitude for the humanitarian aid that was provided to French refugees. 
After some searching, the monument bears the French text: “Ils s’endormaient de parlent du retour de pays” (They slept while talking about returning to their country).

In 2014 it was already 100 years ago that WW1 started and today everybody is so used to cross the open borders and visit each other countries.