How can I get the Bismarck/Hindenburg Class pictures?

[msimon]

In the twitch stream [HOI4: Waking the Tiger - New Germany Focus Tree - Part 2] you can see new pictures for the Bismarck and Hindenburg Classes.

Source:

start at 37:00
How can I get those?

 

[Eaxy]

It seems to be part of a 'secret' DLC - See here

Here is a video of the YouTuber, which was mentioned in the other thread.

The pictures of the two ships are the same.