During WWII, von Behr led reconnaissance troops during action in Poland, France, the Eastern Front, North Africa and Italy.

Valland learned that the trucks which had collected the artworks were heading to the Aubervilliers train station on the outskirts of Paris.

By the 2 August 1944, 148 crates of paintings containing in total 967 paintings, including works by Braque, Cézanne, Degas, Dufy, Gauguin, Modigliani, Picasso, Toulouse-Lautrec and Utrillo had been loaded on five goods wagons waiting to be hooked up to another 48 goods wagons containing confiscated furniture and personal possessions of deported citizens.

Valland was able to give a copy of the Nazi shipment order to Jaujard, which listed the train and goods wagon numbers, the contents of each crate and the destination of each goods wagon (either to Kogl Castle at Sankt Georgen im Attergau in Austria and the Nikolsburg depository in Moravia.

However, two days later the tracks were cleared and being delayed by higher priority trains carrying fleeing Germans and their personal possessions.