|Grand Duke of Hesse and by Rhine|
|Reign||14 August 1806 - 6 April 1830|
|Landgrave of Hesse-Darmstadt|
|Reign||6 April 1790 - 14 August 1806|
|Born||14 June 1753|
|Died||6 April 1830 (aged 76)|
|Spouse||Princess Louise of Hesse-Darmstadt|
|Issue||Grand Duke Louis II|
|Father||Louis IX, Landgrave of Hesse-Darmstadt|
|Mother||Countess Palatine Caroline of Zweibrücken|
Louis was the son of Louis IX, Landgrave of Hesse-Darmstadt, and succeeded his father in 1790. He presided over a significant increase in territory for Hesse-Darmstadt during the imperial reorganizations of 1801-1803, most notably the Duchy of Westphalia, hitherto subject to the Archbishop of Cologne. Allied to Napoleon, Louis in 1806 was elevated to the title of a Grand Duke of Hesse and joined the Confederation of the Rhine, leading to the dissolution of the Empire. At the Congress of Vienna in 1814/15, Louis had to give up his Westphalian territories, but was compensated with the district of Rheinhessen, with his capital Mainz on the left bank of the Rhine. Because of this addition, he amended his title to Grand Duke of Hesse and by Rhine.
In 1844, a 33-meter column called Langer Ludwig (meaning Long Louis), was set up In his commemoration in the middle of the Luisenplatz, the largest square of Darmstadt.
In 1776, he became engaged to Sophie Dorothea of Württemberg, eldest daughter of Frederick II Eugene, Duke of Württemberg. The engagement was broken off so that Sophia Dorothea could marry Louis's recently widowed brother-in-law Tsarevich Paul Petrovich, son and heir of Catherine II "the Great", Empress of Russia. He received a monetary compensation when the engagement was broken.
On 19 February 1777, Louis married his first cousin, Princess Louise of Hesse-Darmstadt ( 15 February 1761 – 24 October 1829), a daughter of Prince George William of Hesse-Darmstadt. Together, they had eight children:
|Ancestors of Louis I, Grand Duke of Hesse|