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The year is 1765 and Danish-German painter Johann Georg Ziesenis (1716 - 1776) has immortalized quite the dog there. Look at its white topknot - and those whiskers! Wow. Oh, yes, there's a Crown Princess of Prussia in there too. Her name was Elisabeth Christine Ulrike von Braunschweig-Wolfenbuttel (or Brunswick-Luneberg).
I'm glad she had such a jolly little friend, because her life was difficult. Married to the future Friedrich Wilhelm II of Prussia, she had one daughter with him before the marriage broke down irretrievably. She salvaged some independence from it, though - read about her here. This portrait was painted in the year of her marriage. I wonder if she knew what rough times lay ahead.