Wondered what flag has only one color, and after about two minutes of research I'm still not really sure which fascist flag is actually just black, but these lyrics are pretty metal:

"With the dagger and the bomb
in the life of terror
when the howitzer is booming
my heart does not tremble.
My beautiful flag
is of a single color,
it is a flame, completely black
that blazes in every heart"
- Giovinezza