He entered the Habsburg military in 1777, at the age of seventeen years, and was a member of the field army in the short War of the Bavarian Succession (1778–79).

While he was assigned to this unit, he participated in the border conflicts between the Ottoman Empire and the Habsburgs, 1787–92, and stormed the fortress at Šabac (German: Schabatz) on the Sava River in Serbia on 27 April 1788.

[4] On 1 January 1790, at Laudon's explicit request, Karl Aloys zu Fürstenberg was promoted to major general; at the end of June of that year, he received the coveted position of second colonel of the 34th Infantry Regiment Anton Esterhazy, where he served as the executive officer for Anton I, Prince Esterházy, the 34th Hungarian Regiment's Colonel and Proprietor.

[5] This was a customary appointment in which a less prominent officer completed the day-to-day administrative duties of the Colonel and Proprietor, who was usually a noble and was often posted in a different assignment, sometimes a different staff location.

[6] Karl Aloys zu Fürstenberg also received the confraternal Order of Saint Hubert from the Duke of Bavaria and married the "elegant" Princess Elisabeth of Thurn und Taxis (1767–1822), that year.

[7] While Karl Aloys zu Fürstenberg fought for the Habsburg cause in Serbia, in France, a coalition of the clergy and the professional and bourgeois class—the First and Third estates—led a call for reform of the French government and the creation of a written constitution.

In 1790, Leopold succeeded his brother Joseph as emperor and by 1791, he considered the situation surrounding his sister, Marie Antoinette, and her children, with greater alarm.

His brigade defended Kehl, a small village immediately across the Rhine from Strasbourg, but most of the action in 1792 occurred further north, in present-day Belgium, near the cities of Speyer and Trier, and at Frankfurt on the Main River.

[9] In the second year of the war, Fürstenberg was transferred to the cavalry of Dagobert Sigmund von Wurmser, in the Army of the Upper Rhine, and placed in charge of the advance guard near Speyer, which was still held by the French.

His first combat action of the war occurred on 3 April, when Custine's infantry attacked him in a bayonet charge near the villages of Bellheim, Hördt and Leimersheim, and afterward at Landau and Lauterbourg.

In the action around Geidertheim, on the Zorn River, he assisted Lieutenant Field Marshal Gabriel Anton, Baron Splény de Miháldy, in repelling a French counter-attack.

[10] In June 1796, Fürstenberg commanded a division of four infantry battalions, 13 artillery pieces, and the Freikorps (Volunteers) Gyulay and secured the Rhine corridor between Kehl and Rastatt.

General Jean Victor Marie Moreau's Army of the Rhine-and-Moselle sought to retain a foothold on the eastern side of the Rhine, following his retreat from southwestern Germany west of the Black Forest.

Karl Aloys zu Fürstenberg was ordered to feint against Riegel, to protect the primary Austrian positions at Rust and Kappel.

Francis II, the Holy Roman Emperor, appointed him as Colonel and Proprietor of the 36th Infantry Regiment, which bore his name until his death in battle in 1799.

[14] The Coalition forces—Austria, Russia, Prussia, Great Britain, Sardinia, among others—achieved several victories at Verdun, Kaiserslautern, Neerwinden, Mainz, Amberg and Würzburg, but in northern Italy, they could neither lift nor escape the siege at Mantua.

Austria withdrew from the territories the army had fought so hard to acquire, including the strategic river crossings at Hüningen and Kehl, as well as key cities further north.

[20] The Army of the Danube met little resistance as it advanced through the Black Forest and eventually took a flanking position on the north shore of Lake Constance.

[21] Instructed to block the Austrians from access to the Swiss alpine passes, Jourdan planned to isolate the armies of the Coalition in Germany from allies in northern Italy, and prevent them from assisting one another.

By crossing the Rhine in early March, Jourdan acted before Archduke Charles' army could be reinforced by Austria's Russian allies, who had agreed to send 60,000 seasoned soldiers and their more-seasoned commander, Generalissimo Alexander Suvorov.

Furthermore, if the French held the interior passes in Switzerland, they could not only prevent the Austrians from transferring troops between northern Italy and southwestern Germany, but could use the routes to move their own forces between the two theaters.

[22] At the outbreak of hostilities in March 1799, Karl Aloys zu Fürstenberg was with his troops in Bavarian territory, just north of the free and Imperial city of Augsburg.

Saint-Cyr did not have the manpower to defend the position, and the entire line fell back to Ostrach, with Fürstenberg's troops pressuring their withdrawal.

[26] On the morning of what they suspected would be the general engagement, Karl Aloys zu Fürstenberg sought out the field chaplain, and requested the sacraments because, as he told his aide, anything can happen during a battle.

[29] Because Souham's assault at the center had been stalled, Charles still had enough men to turn part of his force to fight this new threat, but the Austrians were hard pressed and the action furious.