During the Seven Years' War, he was promoted to lieutenant colonel and made assistant quartermaster general in the Army of the Upper Rhine, a division created by the disbanding of the Loewendal Regiment.

In 1764, Kalb resigned from the army and married Anna Elizabeth Emilie van Robais, the French heiress to a fortune from cloth manufacturing.

[2] In 1768, Kalb traveled to North America on a covert mission from the Duc de Choiseul, the Foreign Minister of France, to determine the level of discontent among colonists towards Great Britain, a major French adversary.

[3] During his four-month trip, Kalb gained respect for the colonists and their "spirit of independence", producing detailed reports for the French government; upon his return to Europe, he expressed a strong desire to go back to colonial America and join their nascent fight against the British.

[4] In July 1777, Kalb returned to North America with his protégé, the Marquis de Lafayette, and joined the Continental Army.

[citation needed] His friend and aide, the Chevalier du Buysson, was seriously wounded blocking additional blows with his own body.

[11] Numerous towns and counties in the U.S. bear his name, including in Alabama, Georgia, Illinois, Indiana,[12] Mississippi, Missouri, New York, Tennessee and Texas.

[13] In 1886, a monument to Kalb was erected on the grounds of the Maryland state house to honor his contributions to the American Revolution.

Since 2006, the Major General Baron DeKalb Army Reserve Center hosts the headquarters of the 200th Military Police Command at Fort Meade, Maryland.