Friedrich Wilhelm von Seydlitz was born on February 3, 1721, at Kalkar in the Prussian Duchy of Cleves. He was the son of Daniel Florian von Seydlitz, a cavalry officer, and Luise von Ilow. His father died while Friedrich was still young, leaving the family with limited means. At thirteen the boy entered the household of Frederick William, Margrave of Brandenburg-Schwedt, as a page. The position introduced him to courtly life, riding, hunting, and military patronage.

Seydlitz showed exceptional skill and daring on horseback. The margrave’s rough household encouraged physical courage but offered little systematic intellectual education. In 1740 Seydlitz entered a Prussian cuirassier regiment as a cornet. He joined the army just as Frederick II began the First Silesian War, giving the young officer immediate experience in fast-moving campaigns against Austria.

He was captured during fighting in 1742 but exchanged after Frederick noticed his conduct. Promotion followed, and Seydlitz served in hussar and cavalry units during the Second Silesian War. At Hohenfriedberg in 1745 he participated in one of Prussia’s most celebrated victories. He developed a critical view of cavalry commanders who launched attacks too early or allowed formations to lose cohesion.

Between wars Seydlitz trained his squadrons with unusual intensity. He emphasized control at speed, close formation, rapid rallying after a charge, and the need for commanders to judge the decisive moment independently. His personal style was bold and sometimes reckless, but his battlefield thinking was disciplined. He married Susanna Johanna Albertine Hacke in 1760, after his reputation was established. By the beginning of the Seven Years’ War, Seydlitz had risen from an impoverished officer’s son to a major general whose horsemanship and tactical insight made him one of Frederick’s most promising cavalry leaders.