Prinsenvlag
An orange, white, and blue [[netherlands|Dutch]] flag associated with [[william_i_of_the_netherlands|Prince William of Orange-Nassau]] (1533–1584). Considered controversial in modern times due to its use by the pro-[[Nazi]] National Socialist Movement (NSB) in the Netherlands in the 1930s.

Not to be confused with the national [[Dutch flag]], which is red, white, and blue.
prince's flag