She was the younger daughter and sixth child of Wilhelm, German Crown Prince, and Duchess Cecilie of Mecklenburg-Schwerin.

Cecilie was born on 5 September 1917 at Cecilienhof Palace in Potsdam, which had only been completed weeks prior to her birth, during World War I and the reign of paternal grandfather, Wilhelm II, as German Emperor and King of Prussia.

During World War II, Cecilie worked at a pharmacy in Potsdam and trained as a nurse with the German Red Cross.

As the Red Army descended on Potsdam at the end of the war, Cecilie was sent to live with Hessian relatives at Schloss Wolfsgarten.

There, she met American Captain Clyde Kenneth Harris, a member of the Monuments, Fine Arts, and Archives Unit who was investigating the Darmstadt Madonna for her cousin, Ludwig, Prince of Hesse and by Rhine.