Prince Friedrich Karl Nikolaus of Prussia (20 March 1828 – 15 June 1885) was the son of Prince Charles of Prussia (1801–1883) and his wife, Princess Marie of Saxe-Weimar-Eisenach (1808–1877). Prince Friedrich Karl was a grandson of King Frederick William III of Prussia and a nephew of Frederick William IV and William I.
As a military commander, the Prince had a major influence on the Royal Prussian Army's advances in training and tactics in the 1850s and 1860s. He commanded one of the armies which defeated the Austrian army at the Battle of Königgrätz in 1866 and the French Army of the Rhine at the Battle of Mars-la-Tour, overseeing the defeat of the Army of the Rhine at the Siege of Metz in 1870.
Biography
Friedrich Karl was born at the Royal Palace in Berlin on 20 March 1828, as the only son of Prince Charles of Prussia, the brother of future German emperor William I. From 1842 to 1846, Frederick Charles was under the military tutelage of then Major Albrecht von Roon. In 1845, the Prince joined the army and was sent to an infantry company. Roon accompanied the Prince to the University of Bonn in 1846. He was the first Hohenzollern prince to study in a university. He became a member of the Corps Borussia Bonn in 1847 and was awarded Prussia's Lifesaving Medal for rescuing a child from the Rhine the same year. After his studies, the Prince went back to his regiment in 1848, where he was promoted to captain. His company was issued the breech-loading Dreyse needle gun and the Prince produced an article on its probable future impact, writing that the troops could be prevented from firing off all their ammunition through good training and discipline. He served on Friedrich Graf von Wrangel's staff during the First Schleswig War of 1848. During the war Friedrich Karl received the Pour le Mérite. He shifted to the cavalry branch in October 1848 and was promoted to major in June 1849. He partook in a campaign in the Baden Revolution of 1849, during which he was wounded twice while leading a Guards Hussar squadron at the battle of Wiesenthal against Baden rebels. He continued to lead his squadron up till 1852.
In 1851, the Prince wrote a radical field manual for light troops, underlining the importance of training individual soldiers to take the initiative and not wait for orders. During the following peace years he was promoted to colonel in 1852 and granted the command of the Guards Dragoon Regiment, where he introduced realistic field exercises and insisted on combat readiness. He became major general and commander of the 1st Guards Cavalry Brigade in 1854 and lieutenant general in 1856. He commanded the 1st Guards Infantry Division from 19 February to 18 September 1857, but resigned after encountering significant opposition to his approach on training. In 1859, he published the study On French Tactics, which highlighted the decisiveness of troop morale. In 1860, the Prince published a military book, titled, "Eine militärische Denkschrift von P. F. K.", which contained a series of reform proposals. As commander of III Army Corps from 1 July 1860 to 17 July 1870, the Prince implemented his reforms and turned his corps into a leader in Prussian military innovation.
Promoted to General der Kavallerie, the Prince took part in the Second Schleswig War of 1864 against Denmark, where he held command over the Prussian troops in the Austro-Prussian expeditionary force and defeated the Danes at the Battle of Dybbøl. In May 1864, he became supreme commander of the Austro-Prussian allied army and conquered Jutland.