Thousands of people gathered in Amsterdam to watch as Dutch King Willem-Alexander laid a wreath at a war memorial, 80 years and a day since the country was liberated from Nazi occupation in 1945.

“Berlin was a heap of rubble — because of these last 10 days, almost everything in the center was ruined,” said Jörg Morre, the director of the Museum Berlin-Karlshorst, located in the building where ...