On 1 July 1862, Louis married Princess Alice, a daughter of Queen Victoria of the United Kingdom, at Osborne House on the Isle of Wight. On the day of the wedding, the Queen issued a royal warrant granting her new son-in-law the style of Royal Highness in the United Kingdom. The Queen also subsequently made Prince Louis a knight of the Order of the Garter. Although an arranged marriage orchestrated by the bride's father Albert, Prince Consort, the couple did have a brief period of courtship before betrothal and wed willingly, even after the death of the Prince Consort left Queen Victoria in a protracted state of grief that cast a pall over the nuptials. Becoming parents in less than a year following their marriage, the young royal couple found themselves strapped financially to maintain the lifestyle expected of their rank. Princess Alice's interest in social services, scientific development, hands-on child-rearing, charity and intellectual stimulation were not shared by Louis who, although dutiful and benevolent, was bluff in manner and conventional in his pursuits. The death of the younger of their two sons, Frittie, who was afflicted with hemophilia and suffered a fatal fall from a palace window before his third birthday in 1873, combined with the wearying war relief duties Alice had undertaken in 1870, evoked a crisis of spiritual faith for the princess in which her husband does not appear to have shared. In 1866 the Austrians suffered defeat in the Austro-Prussian War and the Hessian grandduchy was in jeopardy of being awarded as the spoils of war to victorious Prussia, which annexed some of Austria's other allies, a fate from which Hesse-Darmstadt appears to have been spared only by a cession of territory and the close dynastic kinship between its ruler and the Emperor of Russia. In the Franco-Prussian War provoked by Bismarck's manipulation of the Ems telegram in 1870, Hesse and by Rhine this time found itself a winning ally of Prussia's, and Prince Louis was credited with courageous military service, especially at the Battle of Gravelotte, which also afforded him the opportunity of mending the previous war's grievances with the House of Hohenzollern by fighting on the same side as his brother-in-law and future emperor, Prince Frederick of Prussia. In March 1877, Louis became heir presumptive to the Hessian throne when his father died and, less than three months later, found himself reigning grand duke upon the demise of his uncle, Louis III. A year and a half later, however, Grand Duke Louis was stricken with diphtheria along with most of his immediate family, from which he recovered but to which his four-year-old daughter Marie succumbed, along with his wife of 16 years. From then on, he reigned and raised his five surviving children alone.
Military career
During the Austro-Prussian War of 1866, Louis commanded the Hessian cavalry in support of the Austrian side. In the 1870–71 Franco-Prussian War, Louis led the Hessian contingent of the armies of the North German Confederation.
On 13 June 1877, he succeeded his uncle as Grand Duke of Hesse, taking the name "Ludwig IV".
Second marriage
Grand Duchess Alice having died in 1878, Louis IV contracted a morganatic marriage on 30 April 1884 in Darmstadt with Countess Alexandrina Hutten-Czapska, daughter of Count Adam Hutten-Czapski and Countess Marianna Rzewuska. She was the former wife of Aleksander von Kolemin, the Russian chargé d'affaires in Darmstadt. But the couple, facing objections from the Grand Duke's in-laws, separated within a week and the marriage was annulled within three months. As a compensation, she received the title Countess von Romrod on 31 May 1884. Alexandrine later married for the third time to Basil von Bacheracht.
Death
Grand Duke Ludwig IV died on 13 March 1892 of a heart attack in the New Palace in Darmstadt and was succeeded by his son, Ernest Louis. His remains are buried at Rosenhöhe, the mausoleum for the Grand Ducal House outside of Darmstadt.
Issue
Honours
;German orders and decorations ;Foreign orders and decorations
