The Eyewitness Museum in Beek, which displays dioramas about World War Two, was broken into by a gang of six thieves who rammed the door down in August.
They made off with €1.5m-worth of exhibits in just six minutes after cutting through display cases to take rare, valuable items.
“They knew what they were looking for,” museum owner Wim Seelen told the Trouw newspaper.
“The only thing I can think of is that someone ordered it. Many of the stolen items are so unique you cannot sell them.
“Our world is a small one. As soon as something emerges from Beek or Ossendrecht, it will be immediately known.”
Similarly, in early October the Oorlogsmuseum (or Overloon War Museum) in Ossendrecht, which also focuses on World War Two exhibits, was broken into overnight.
SS uniforms, parachutes and firearms worth hundreds of thousands of euros were stolen.
Jan de Jonge, the museum’s owner, said the raid was targeted very specifically at German memorabilia.
“They drilled holes in the door to get the handle down from the inside,” he said, reports The Guardian. “I didn’t hear anything while I was sleeping on the other side of the wall.
“SS uniforms, daggers, helmets, emblems, caps, parachutes, firearms, binoculars, you name it. There’s nothing left. The firearm is very rare, but I was able to display it in this museum.
“German stuff, they didn’t take anything from the allies. A French corner, English, Canadian: all intact. German material, especially clothing, is rare.”
He added that at least 15 mannequins dressed in uniforms had all been taken.
The collection is irreplaceable; it was privately owned and uninsured.
Other museum owners are now taking extra measures to protect rare exhibits.
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The 1940-1945 War Museum in Loon op Zand is removing forks owned by Adolf Hitler and prominent Nazi leader Heinrich Himmler, Hitler Youth memorabilia and various Nazi uniforms from display; the Oorlogsmuseum is returning rare books it had on loan, including the Book of the Dead from Auschwitz; and Arnhem War Museum plans to build roadblocks to prohibit large vehicles from entering.
“It is very disturbing,” John Meulenbroeks, director of the Eventful Years Museum in north Brabant, told the Omroep Brabant newspaper. “It seems as if this is on request. It is very specific material from the German SS that is sought worldwide. There are collectors of that German material everywhere.”