Reventlow had a military career and fought in the Danish contingent against the French during the
War of the Grand Alliance. In 1701 he was sent at the head of the Danish troops to fight the French in
Italy during the
War of Spanish Succession, serving under
Prince Eugene of Savoy (1663–1736). He took part in the
Battle of Höchstädt in 1704 and was severely wounded in the
Battle of Cassano in 1705. At the
Battle of Calcinato on 19 April 1706, Count von Reventlow was pitted against General
Louis Joseph de Bourbon, duc de Vendôme (1654–1712), in a battle resulting in a French victory. His forces were divided as Reventlow was in command of the imperial army at both
Montichiari and
Calcinato. ==Personal life==