{{Infobox Personnalité militaire
| nom                    = Leopold Ludwig Hermann von Boyen
| image                  = Boyen.jpg
| tailleimage(en px)     = 250
| surnom                 =
| datedenaissance        = 20 juin 1771
| lieudenaissance        = Kreuzburg (Prusse-Orientale)
| datemortaucombat       =
| lieumortaucombat       =
| datededeces            = 15 février 1848
| lieudedeces            = Berlin
| ageaudeces             =
| paysdorigine           = 
| allegeance             =
| grademilitaire         = Generalfeldmarschall
| arme                   =
| annéedebutdecarriere   =
| annéefindecarriere     =
| conflit                =
| commandement           =
| faitsdarmes            =
| distinctionsprincipales=
| hommage                =
| autresfonctions        = Ministre de la Guerre <br/> de 1814 à 1819 <br/> puis de 1841 à 1849
| famille                =
| legende                =
}}
'''Leopold Ludwig Hermann von Boyen''' (né le 20 juin 1771 à Kreuzburg (Prusse-Orientale), mort le 15 février 1848 à Berlin) était un général qui a contribué à réformer l'armée prussienne au début du . Il fut également ministre de la Guerre du  au 6 octobre 1847.

== Carrière militaire ==
Boyen est issu d'une famille de la petite noblesse prussienne. Après la mort prématurée de ses parents Boyen rejoint l'armée en 1784. En 1788 il est nommé sous-lieutenant à l'académie militaire de Königsberg, où il participe à certaines des conférences d'Emmanuel Kant.

De duc de Brunswick, et est blessé à la Gerhard von Scharnhorst. 

En 1810 Boyen devient directeur du Département général de la guerre, mais après la conclusion de l'alliance entre la Prusse et la France en Vienne et Frédéric-Guillaume III le nomme chef d'état-major du 3 corps d'armée. À ce titre, Boyen participe aux batailles et escarmouches de 1813 et 1814 et obtient le grade de major-général.

== Ministre de la Guerre ==
Après le traité de Paris, (le 30 mai 1814) Boyen occupe les  fonctions de ministre de la Guerre. Il complète la mise en place de la ''Landwehr'' (armée de réserve) et en 1818 est nommé lieutenant-général. Il lutte en vain contre la montée des forces réactionnaires qui mettent en danger la large base populaire de la Landwehr, et a démissionne en 1819.

thumb|Herrman von Boyen

'''Leopold Hermann Ludwig von Boyen''' (Prussian army officer who helped to reform the Prussian Army in the early 19th century. He also served as minister of war of Prussia in the period 1 March 1841 - 6 October 1847.

==Life==

Born in Kreuzburg (today Slavskoye, Russia) in East Prussia, Boyen joined the army in 1784 in Königsberg. In 1788, as a newly-minted second lieutenant, he took up a post in the military academy in Königsberg, where he also attended some of the lectures of Immanuel Kant.

From 1794-96, Boyen took part in the Polish campaign as Adjutant to General von Günther. In 1799, he became a Captain. He served in the war of 1806 on the General Staff of the Duke of Brunswick, and was wounded at the Battle of Auerstädt (14 October 1806). After the Treaty of Tilsit  (July 1807) he became a Major and a member of Gerhard von Scharnhorst's commission for military re-organisation.

By 1810 Boyen had become Director of the general department of war. In the re-constitution of the Prussian army he functioned as Scharnhorst's most diligent helper, but after the conclusion of the alliance between Prussia and France in 1812 he resigned his commission as a Colonel and visited Vienna and St Petersburg.  The events of 1813 saw him recalled to the Prussian service: as a colonel he accompanied the Russian army from its base in Battle of Lützen (2 May 1813) he had charge of the border guards and ultimately the defence of Berlin. But during the truce King Frederick William III named him Chief of General Staff of the 3rd Army Corps. As such, Boyen participated in the battles and skirmishes of 1813 and 1814 and gained promotion to Major-General.

After the first Peace of Paris (30 May 1814) Boyen took up his appointment as War Minister. He completed the setting up of the ''Landwehr'' reserve (begun during the war) and in 1818 became a Lieutenant General. He struggled in vain against growing reactionary forces which endangered the broad popular base of the ''Landwehr'', and resigned in 1819.
thumb|The tomb of Boyen at the Invalidenfriedhof in Berlin
For 21 years Boyen lived in retirement, occupying himself with historical studies, until King Frederick William IV, immediately after ascending the throne, recalled him to active service, and promoted him to General of the Infantry. In March 1841 he once again took over the War Ministry, though without achieving a great influence in the general political situation. He resigned in November 1847, received the rank of Field Marshal, and died on Lötzen in East Prussia after him.