I’ve always liked the flag of Prussia because it just looks so complex, so out of boredom I decided to look up little bits of info about what each part of the flag means. This is what I found out:

• The color white symbolizes the religious purity of the state’s foundation, the Teutonic Knights.
• The color black symbolizes determination and the defeating of enemies. 
• The black eagle itself represents Prussia as a former part of the Holy Roman Empire.
• If you look closely, you can see the crosses both on the wings of the eagle and on the globe. This represents Prussia as a Christian crusader (but of course, the symbol eventually evolved to become a symbol of the Nazi party over time).
• The crown and staff represents the glory of Prussia’s monarchs.
• Lastly, the symbol on the breast of the eagle is not “P” for “Prussia”.  It is actually the combination of the initials (F.R.), for Fridericus Rex, a Latin term for…Friedrich the Great, one of Prussia’s most innovative and well-adored kings.  Thus, this symbol is dedicated solely to “Old Fritz”.