He entered the imperial cavalry in 1788, fought in 1789 under Lacy and Loudon against the Turks, distinguished himself by his bravery, and became major in 1792. In the French campaign of 1793 he served in the advanced guard of the army commanded by Prince Josias of Coburg, and at Cateau Cambresis in 1794 his impetuous charge at the head of his regiment, vigorously supported by twleve British squadrons, broke a whole corps of the French, killed and wounded 3000 men, and brought off 32 of the enemy's guns. He was immediately decorated with the cross of the Maria Theresa order.
After taking part in the battles of Amberg and Würzburg in 1796 he was raised to the rank of major-general, and in 1799 he was promoted lieutenant field marshal. At the defeat of Hohenlinden in 1800 his promptitude and courage saved the right wing of the Austrian army from destruction, and he was afterwards entrusted by the archduke Charles with the command of the rearguard. In the war of 1805 he held command of a division under Mack, and when Ulm was surrounded by Napoleon in October he was one of the brave band of cavalry, under the archduke Ferdinand, which cut its way through the hostile lines. In the same year he was made a commander of the order of Maria Theresa and in 1809 he received the Golden Fleece.
When in 1808, in view of a new war with France, Austria decided to send a special envoy to Russia, Schwarzenberg, who was persona grata at the court of St Petersburg, was selected. He returned, however, in time to take part in the battle of Wagram, and was soon afterwards promoted general of cavalry. After the peace of Vienna he was sent to Paris to negotiate the marriage between Napoleon and the archduchess Maria Louisa. The prince gave a ball in honour of the bride on the ist of July 1810, which ended in the tragic death of many of the guests, including his own sister-in-law, in a fire.
Napoleon held Schwarzenberg in great esteem, and it was at his request that the prince took command of the Austrian auxiliary corps in the Russian campaign of 1812. The part of the Austrians was well understood to be politically rather than morally hostile, and Schwarzenberg gained some minor successes by skilful manoeuvres without a great battle; afterwards, under instructions from Napoleon, he remained for some months inactive at Pultusk. In 1813, when Austria, after many hesitations, took the side of the allies against Napoleon, Schwarzenberg, recently promoted to be field marshal, was appointed commander-in-chief of the allied Grand Army of Bohemia. As such he was the senior of the allied generals who conducted the campaign of 1813-1814 to the final victory before Paris and the overthrow of Napoleon.
It is the fashion to accuse Schwarzenberg of timidity and over-caution, and his operations can easily be made to appear in that colour when contrasted with those of his principal subordinate, the fiery Blücher, but critics often forget that Schwarzenberg was an Austrian general first of all, that his army was practically the whole force that Austria could put into the field in Central Europe, and was therefore not lightly to be risked, and that the motives of his pusillanimity should be sought in the political archives of Vienna rather than in the text-books of strategical theory. In any case his victory, however achieved, was as complete as Austria desired, and his rewards were many, the grand crosses of the Maria Theresa and of many foreign orders, an estate, the position of president of the Hofkriegsrath, and, as a specially remarkable honour, the right to bear the arms of Austria as an escutcheon of pretence. But shortly afterwards, having lost his sister Caroline, to whom he was deeply attached, he fell ill. A stroke of paralysis disabled him in 1817, and in 1820, when revisiting Leipzig, the scene of the Volkerschlacht that he had directed seven years before, he was attacked by a second stroke. He died there on the 15th of October.
His eldest son, Friedrich, prince zu Schwarzenberg (1800-1870), had an adventurous career as a soldier, and described his wanderings and campaigns in several interesting works, of which the best known is his Wanderungen eines Lanzknechies (1844-1845). He took part as an Austrian officer in the campaigns of Galicia 1846, Italy 1848 and Hungary 1848, and as an amateur in the French conquest of Algeria, the Carlist wars in Spain and the Swiss civil war of the Sonderbund. He became a major-general in the Austrian army in 1849, and died after many years of well-filled leisure in 1870. The second son, Karl Philipp (d. 1858), was a Feldzeugmeister; the third, Edmund Leopold Friedrich (1803-1873), a field marshal in the Austrian army. Of Schwarzenberg's nephews, Felix, the statesman, is separately noticed, and Friedrich Johann Josef Coelestin (1800-1885) was a cardinal and a prominent figure in papal and Austrian history.
See Prokesch-Osten, Denkwurdigkeiten aus dem Leben des Feld-marschall's Fürsten Schwarzenberg (Vienna, 1823); Berger, Das Furstenhaus Schwarzenberg (Vienna, 1866), and a memoir by the same hand in Stroffleur's Ost. Militärzeitschrift, 1863.