Young von Grawert entered military service in 1759, during the Third Silesian War, when he enlisted for 12 years and right in time for the Battle of Kunersdorf.

When the transformation of the army was proposed after the death of Frederick the Great, then Major Grawert was drafted to Berlin and worked there for several months to establish a military college, but in 1788 he was transferred to the Infantry Regiment Duke of Brunswick in Halberstadt and soon promoted to lieutenant colonel.

On 28 January 1793 he was promoted to colonel and, when Quartermaster General Theodore von Pfau was killed at the Battle of Trippstadt, Grawert replaced him.

Both Prussian commanders, the Duke of Brunswick and Field Marshal Möllendorf, were completely pleased with him; and he became famous in the battles and campaigns of the First Coalition, proving his talents as a practical warrior and as a war writer.

Grawert's correspondence with the Duke of Brunswick, which contains a description of events for about thirty years, is considered a notable source on the military history of Prussia during the late 18th and early 19th centuries.