Von Schmettau was born in
Berlin. His mother, Marie de la Fontaine, belonged to a Huguenot family. His father died in 1707, as Royal Prussian secretary to the ambassador in London. In 1699, he joined the military and served under numerous flags during his career. He started as a Danish Cuirassier, under the command of his uncle William. In 1703, he joined the
Margrave of Anspach Dragoons, as a lieutenant, where another uncle, Gottlieb Schmettau, was chief. Schmettau experienced his baptism of fire at the
Battle of Blenheim. A little later, he became captain and company commander, and was promoted to Major in 1707, and lieutenant colonel in 1708. He was Adjutant General of the
Prince of Hesse, at the
Battle of Malplaquet. In 1714, Schmettau went with his regiment in the
Electorate of Saxony. On 22 October 1716, he was promoted to colonel in the artillery. He went into the service of the
Habsburgs on 7 April 1717. There Schmettau took part in the
conquest of Belgrade. On 22 March 1719, he was Field General, and came to Sicily as
Quartermaster General. His achievements as an artilleryman and fortress builder impressed the Emperor and
Prince Eugene of Savoy. In 1720, during the
War of the Quadruple Alliance, he led the
Capture of Messina (1719), and in 1732 with Corsica, he led the campaign against Sardinia and France. On 27 October 1733, he was promoted to Lieutenant Field Marshal. He commanded the O'Gilvy Infantry Regiment (No. 46); with his regiment, he then took part in the
War of the Polish Succession. In the years 1737–1739, during
Russo-Austrian-Turkish War, he was governor of
Timișoara. Unhappy not to be given command of the field army, Schmettau attempted to defect to Venice, but this failed. Although he was promoted to Imperial Field Marshal on 19 March 1741, he continued to pursue his intention to find a new employer. He was welcomed into the Prussian Army on 12 June 1741. Schmettau immediately became Prussian Field Marshal without having previously led any troops in Prussia. On 18 January 1742, Schmettau was awarded the
Order of the Black Eagle. He left the service in 1742. ==Diplomacy==