Wilhelm Graf zu Schaumburg-Lippe was a German ruler of the County of Schaumburg-Lippe-Bückeburg and a military commander in the Seven Years' War. He held notable titles, including Generalfeldzeugmeister of the Electorate of Brunswick-Lüneburg and British field marshal. Wilhelm was born in London to Albrecht Wolfgang, Count of Schaumburg-Lippe, and his first wife, Countess Margarete Gertrud of Oeynhausen. His mother was rumored to be an illegitimate daughter of George the First of Great Britain and his mistress Ehrengard Melusine von der Schulenburg.
Wilhelm accompanied his father during the War of Austrian Succession while in Dutch service and was present at the Battle of Dettingen in 1743. Later, he fought in the Austrian campaign in Italy. After his father's death, he succeeded him as Count on 25 October 1748. As Count and General of the Artillery, he sided with Prussia during the Seven Years' War. Wilhelm distinguished himself at the Battle of Minden as the head of the allied artillery and was rewarded with the overall command of the allied artillery.
In 1762, at the request of the Marquis of Pombal, Wilhelm led the allied troops in Portugal against the Spanish invasion. He conducted a brilliant defensive campaign, even though the enemy had a three-to-one superiority in numbers. Despite always being outnumbered, the enemy never dared to risk an all-out attack. He died at Wölpinghausen, and his cousin, Philipp II. Ernst, succeeded him as Count of Schaumburg-Lippe-Bückeburg.
Wilhelm was married to Countess Marie Barbara Eleonore of Lippe-Biesterfeld, and they had two children, Countess Emilie and an unnamed son. He also had two children, Joseph and Olimpia Petronellia, with an unknown woman. Olimpia was later recognized by her father's cousin, Philip II Ernst, and her name was changed to Olímpia Patronellia Ernestina de Schaumburg-Lippe. Countess Olimpia died on 25 November 1822. Wilhelm was an influential military theorist and an advocate of defensive warfare. One of his best-known slogans is: "Kein anderer als der Defensivkrieg ist rechtmäßig!"