Kleist served in the Napoleonic Wars and fought at Jena. In 1807 he went on extended leave but by 1808 he was put in command of an infantry brigade and the next year he was made commandant of Berlin. During the War of Liberation he was given a corps with which he fought in the battles of Kulm and Leipzig. In 1814, he was given the title Count of Nollendorf (from the German name of the town Nakléřov, now part of Petrovice in the Czech Republic) for his decisive role in this battle.

After Leipzig, Kleist blockaded the fortress of Erfurt, bringing about its surrender after which, in early 1814, he marched his troops into France, where his corps was attached to Blücher's army. He then fought in the battle of Laon and in the attack on Paris. At the end of the war Kleist was promoted to the rank of General der Infanterie. During the Hundred Days, Kleist was given command of a Prussian corps (the North German Corps) which was to operate independently from Blücher's Army of the Lower Rhine; he was therefore not involved in the battles of Ligny and Waterloo.

^Regarding personal names: Graf was a title before 1919, but now is regarded as part of the surname. It is translated as Count. Before the August 1919 abolition of nobility as a legal class, titles preceded the full name when given (Graf Helmuth James von Moltke). Since 1919, these titles, along with any nobiliary prefix (von, zu, etc.), can be used, but are regarded as a dependent part of the surname, and thus come after any given names (Helmuth James Graf von Moltke). Titles and all dependent parts of surnames are ignored in alphabetical sorting. The feminine form is Gräfin.