In European countries, political parties and ideologies tend to be associated with colors. The most famous example, which you've probably heard, is that Communists (and often Socialists too) are associated with the color red. A few other examples are:

• Black is often associated with center-right or right-wing Christian-based parties, like the CDU/CSU union in Germany, or the Austrian People's Party. In Italy, however, it was the color of the Fascist party so nobody uses it there.
• Green obviously with Green and other environmentalist parties
• Yellow is typically associated with liberal parties
• Blue is often right-leaning parties, for example, the Freedom Party of Austria or the Conservative Party of the UK.

Bismarck was a monarchist and extreme conservative- firmly a "white" (although he wasn't actually in a political party). He fought hard to strengthen the monarchy in Germany, and the suppress the growing socialist movement of the late 1800s. His efforts can be seen as revolutionary, in counter to the socialist revolutionaries of the time.