De Kalb was born in Huettendorf, Bavaria, on June 19, 1721. This peasants' son later learned French, English, and sufficient social skills to obtain a substantial military commission in the Lowendal Regiment of the French army. He served with this unit throughout the War of Austrian Succession. In 1763, at the battle of Wilhelmstahl, he won the Order of Military Merit that gave him his baronic title.
Five years later, he traveled to America on a secret mission for France to determine the extent of colonial discontent there. With his protégé, the Marquis de Lafayette, De Kalb went to America again in 1777. They joined the Continental Army. De Kalb served in an administrative capacity. During the spring of 1780, he received his first field command. He led the American army to relieve the besieged Charleston, South Carolina. At the battle of Camden later that summer, he was mortally wounded and captured by the British. De Kalb died on August 18, 1780.