By the end of the War of the First Coalition, at the age of 35, he had achieved the rank of Field Marshal. During the War of the Second Coalition, he fought in the first two battles of the German campaign, at Ostrach on 21 March 1799, and at Stockach on 25 March 1799. At the latter action while leading a regiment of grenadiers, he was hit by French case shot and knocked off his horse. He died shortly afterward. As the third son of a cadet (junior) branch of the Fürstenberg princely family, Karl Aloys was prepared for a military career. His tutor, Lieutenant Ernst, was in active service in the Habsburg military, and took six-year-old Karl Aloys on maneuvers with him. In this way, he learned as a child the Habsburg military manual, and came into contact with important military men who later furthered his education and career; he also acquired an honorary rank as "Kreis-Obristen", or Colonel of the Imperial Circle, by the time he was ten years old. As a youth, in 1776, he met the Habsburg war minister Count Franz Moritz von Lacy and Baron Ernst Gideon von Laudon; he was also invited to dine with Emperor Joseph II. He started his service in 1777 as a "Fähnrich" (ensign) in the Habsburg military organization. He saw his first field service during the War of the Bavarian Succession (1777–78), although he was not involved in any battles. In 1780, at the age of twenty years, he was promoted to captain, and assigned to the 34th Infantry Regiment, also known as the "Anton Esterházy", named for Paul II Anton Esterházy, the general of cavalry, field marshal of the Seven Years' War, and ambassador to Britain. 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. For his action at Šabac, he was personally commended by the Emperor; on the following day, he was promoted to major and given command of a grenadier battalion. 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 Antal, Prince Esterházy de Galántha, the 34th Hungarian Regiment's Colonel and Proprietor.