What did "black Friday" connote in 1966 Germany?

Question

In a paragraph in a 1966 German book I’m translating, the author on describing the German sense of humor during hard times writes:

Unsere Väter muß einigen Spaß vertragen. Im Angesicht von Weltkriegen, Inflationen, Wirtschaftskrisen, schwarzen Freitagen [5], Not und Tod. Die deutsche Geschsichte im Spiegel des Witzes ...

[Our fathers must have some fun, in the face of world wars, inflation, economic crises, black Fridays [5], distress and death. The German story [is] in the mirror of the joke; ...]

After a bit of research I think that the connotation of “black Friday” in its 1966 context refers to the date of the East German government's announcement over the radio on Friday, August 10, 1961, that it was going to build a wall in Berlin which would separate the DDR’s sector in Berlin from the Allied sectors of that city.

Is my assumption on the meaning of the “black Friday” phrase correct?

Answer 1

I have never heard the day of the beginning of the Berlin wall build called "schwarzer Freitag". That date (or rather, the Sunday after that date, when borders were closed and the first bricks were laid) is typically referred to as "Tag des Mauerbaus" - even if it took longer than one day. 13th of August, 1961 was a Sunday, so, if at all, it would, supposedly, need to be named a "black Sunday". Also, your "radio announcement" story seems to be a misinformation: East German people were not informed up-front that there was a wall to be built - Why should they have done that - provoke a mass exodus before borders were closed?.

The idiom "schwarzer Freitag" was imported by stock traders into German with the 1929 "international" Black Friday and has almost exclusively been used for financial disasters since then.

Answer 2

I don't think that you are correct, especially because the German text is talking about "schwarzen Freitagen", so it is plural and cannot refer to one day alone.

From the context talking about inflation and economic crises it also seems more related to a financial disasters.

The German wikipedia page about Schwarzer Freitag says that this term in a german speaking context often refers to the crash of the Berlin stock exchange on May 13, 1927 as well as the of the Vienna Stock exchange on May 9, 1873. However it is also is used to refer to other financial crises.