[Below: This postcard was canceled on September 18, 1939. On May 10, 1940, Germany invaded Luxembourg, the Netherlands, and Belgium, so this postcard isn't from the German occupation, but it has other significance, see below.]

[Below: Reverse. The SS 'Alex van Opstal' was a 6,000 ton merchant vessel completed in 1937, just two short years from being sunk by sunk by U-26. It's crew of 57 all survived. It was torpedoed and sunk on September 15, 1939, just two weeks into WWII. It's interesting that this postcard was sent just three days after the Van Opstal was sunk. This guy wasted no time writing the 'International Stamp Bureau' regarding 'duplicates' which can only mean postage stamps for his collection. This guy was a serious stamp collector and wasn't about to let a sunken ship or a world war slow down his collecting.]

[Below: The 'Alex van Opstal' in better days. She shouldn't have done war business with Germany's enemies.]

[Below: 1943 envelope canceled and chemically tested for secret messages (the blue line). Front.]

[Below: The back is also chemically tested. Back.]

[Below: 1940s censored enveope. Front.]

[Below: Back.]