Louise of Prussia (Luise Marie Elisabeth; 3 December 1838 – 23 April 1923) was Grand Duchess of Baden from 1856 to 1907 as the wife of Grand Duke Frederick I. Princess Louise was the second child and only daughter of Wilhelm I, German Emperor, and Augusta of Saxe-Weimar-Eisenach. She was the younger sister of Frederick William ("Fritz"), the future German Emperor Frederick III, and aunt of Emperor Wilhelm II.
Princess of Prussia
Louise Marie Elisabeth was born on 3 December 1838 to Prince Wilhelm of Prussia and his wife Princess Augusta of Saxe-Weimar-Eisenach. Louise was named after her grandmothers, Louise, Queen of Prussia and Grand Duchess Maria Pavlovna of Russia and was known as "Vivi" in her family. Her parents were a happy but tense couple, and Louise had only one other sibling,
Prince Frederick William, who was seven years older. Upon her birth, Augusta declared that her duty in perpetuating the Hohenzollern dynasty was complete.
While Wilhelm showed some outward affection to his only son, he lavished attention on Louise, and often his unexpected visits to her schoolroom resulted in them playing together on the floor. Mother and daughter however were not close, with Augusta's presence filling Louise up with awe; one account states that when Augusta encountered her daughter, Louise "involuntarily drew herself up to her full height, and sat stiff and constrained as for her portrait, while she inwardly trembled lest her answers should prove incorrect".
Grand Duchess of Baden
left|thumb|190px|Grand Duchess Louise and [[Grand Duke Frederick I of Baden]]
Louise was betrothed to Frederick, Prince Regent of Baden, in 1854, and they married 20 September 1856 at Neues Palais in Potsdam.
Louise and Frederick disliked the stiffness of the Karlsruhe court, and gladly escaped to their castle on the island of Mainau. They were popular in Baden, and everyone spoke with affectionate pride of their grand duke and duchess in Constance, where the couple had a summer residence.
Later years
thumb|upright|200px|Princess Louise of Prussia in 1856, portrait by [[Franz Xaver Winterhalter]]
thumb|upright|200px|Grand Duchess Louise of Baden, 1860s
Louise was a great friend of Alice, Grand Duchess of Hesse, her sister-in-law's younger sister; i.e., Alice was the sister of Victoria, Louise's brother Frederick William's wife, both sisters being daughters of Queen Victoria. The two often visited each other. In Queen Victoria's letters, she and Frederick were always referred to with pleasure or sympathy as good Fritz and Louise of Baden. Though friends as young girls, Louise and her sister-in-law Victoria, Princess Royal ("Vicky") always had a "none-too-friendly rivalry", particularly when comparing their children: while Vicky's eldest son Crown Prince Wilhelm was born with a deformed arm, Louise apparently could not resist bragging that her three children were healthier and bigger at the same age.
Louise maintained a correspondence with Florence Nightingale, who believed the Grand Duchess' letters could have been written by "any administrator in the Crimean War". The Grand Duchess also had a lifelong friendship with Clara Barton, whom she met during the Franco-Prussian War.
Widowhood
Within two years, four of Louise's closest family members died - her father, brother, younger son and mother. Her sister in law Vicky, now the Dowager Empress Frederick, took sympathy on Louise and persuaded her mother, Queen Victoria, to confer the Royal Order of Victoria and Albert, First Class, on her. Louise, as well as the rest of the family, left the palace via a backway and fled to the Zwingenberg palace in the Neckar valley. By permission of the new government, they were allowed to stay at the Langenstein Palace, which belonged to a Swedish noble, Count Douglas.</blockquote>
Honours
;Decorations and awards
;Honorary military appointments