Since Louis IX showed little interest in his children, it was vital to get Louise married off and a matter also in the hands of her mother, becoming known as the "great Landgräfin" and von Zweibrücken due to her expert international dynastic politics in ancien regime Europe.

Tsarina Catharine II decided Louise was unsuitable as a wife for the grand prince and future Tsar Paul, preferring her sister Wilhemine.

Nevertheless, this journey was not without influence on Louise, since on the way to Russia Caroline had learned of another female regent of a small German state – Anna Amalia.

At the end of this acquaintance, under the influence of the governor in Erfurt from the Archbishopric of Mainz, Karl Theodor Anton Maria von Dalberg, the 18-year-old Louise was betrothed to the young knight Carl August of Sachsen-Weimar.

The marriage was wholly dynastic in purpose (her sisters were married off to heir to Prussia and the Tsarevitch), consolidating the duchy of Saxe-Weimar's place at the heart of the Holy Roman Empire.

Primary and secondary sources agree that it was as unhappy, with Louise (noted for her delicacy and timidity) had difficulty fitting in at court and remained in the shadow of her mother-in-law, the dowager duchess Anna Amalia.

Goethe was court poet and minister to her husband (and his companion in his extra-marital affairs), but was moved by her charm, noble-heartedness and her eyes "the colour of cornflowers".

(J'en sais une, mince comme lys/ Dont la fierté n'est qu'innocence./ Nul – pas même Salomon – n'en vit de pareille.

The battle of Jena-Auerstedt (14 October), led to the defeat of the Prussian-Saxon forces and the total submission of all the German states to France and precipitated the fall of the Holy Roman Empire.

Nevertheless, at her husband's request and inspired by the example of the German patriot queen Louise of Prussia, she managed to arrange the French plundering of the area so that Weimar got off lightly compared to the university-city of Jena.