WW1 remembrance postcard

This is a special issued French remembrance postcard.
It has 3 stamps on the front side with each a different time stamp with in total 10 years in between.
First date is November 1968, second is November 1973 and last one is November 1978.
So, 50 years, 55 years and 60 years after the end of WW1.

Never seen this before!