He was an illegitimate son of August the Strong, King of Poland, Grand Duke of Lithuania and Elector of Saxony, and his mistress Fatima (or Fatime) who was of Turkish origin.

Frederick Augustus moved to the estates of the Spiegel Family, but his father cared about his education, which led him among other things to go to Paris, where he found his half-sister Anna Karolina (the later countess Orzelska) and brought her to Dresden.

On 8 October 1724 Frederick August, now Count Rutowski, obtained of his father the highest decoration of the Wettin lands, the Order of the White Eagle, which gave him the rank of an Oberst of the Saxon Army.

After a journey to Munich and Venice, Rutowski arrived in February 1725 at the court of the King of Sardinia and Duke of Savoy, Victor Amadeus II in Turin, where he took command of the Piedmont regiment and was garrisoned in Alessandria.

During the following years, in the War of Polish Succession, he participated in the campaigns in Poland and on the Rhine, becoming Lieutenant-General on 1 January 1736 and Commander of the Garde du Corps.

During the next peace years, he did not succeed in spite of multiple efforts, to avert the cutbacks in the Saxon Army by the prime minister Brühl, which seriously reduced its effectiveness.