Censorship in wartime is nothing special. What happened with this postcard from the occupied Netherlands (31-05-1940) to Batavia, Dutch East Indies, is therefore not rare. The two-line red stamp “Gecensureerd” (censored) is very common.
The back (and also the front) was completely used by the writer, but the majority was scratched away and is therefore unreadable. The removal of text by the censor is nothing special, although it is usually done with black ink or – for a letter – by cutting out the relevant piece.
What is special here however is that by placing the (also rare) ellipse-shaped stamp “Ec. C. 10” there is evidence that the censor was indeed the culprit. After all, a jar of black ink (to blacken the relevant parts of the text) would very probably have been readily available…