- Frederick William I (German: Friedrich Wilhelm I.; 14 August 1688 – 31 May 1740), known as the Soldier King (German: Soldatenkönig), was King in Prussia and Elector of Brandenburg from 1713 until his death in 1740, as well as Prince of Neuchâtel. Frederick William instituted major military reforms, and expanded the army to new limits. He also made efforts to reduce crime and corruption in his state and centralized his authority during his 27 years reign, cementing Prussia as a regional power. His other notable decisions would be the selling of Prussian overseas colonies and the foundation of the Canton system, as well as the conquest of the port of Stettin. He was succeeded by his son, Frederick the Great.
- My third maxim was to endeavour always to conquer myself rather than fortune, and change my desires rather than the order of the world, and in general, accustom myself to the persuasion that, except our own thoughts, there is nothing absolutely in our power; so that when we have done our best in respect of things external to us, all wherein we fail of success is to be held, as regards us, absolutely impossible and this single principle seemed to me sufficient to prevent me from desiring for the future anything which I could not obtain, and thus render me contented; for since our will naturally seeks those objects alone which the understanding represents as in some way possible of attainment, it is plain, that if we consider all external goods as equally beyond our power, we shall no more regret the absence of such goods as seem due to our birth, when deprived of them without any fault of ours, than our not possessing the kingdoms of China or Mexico; and thus making, so to speak, a virtue of necessity, we shall no more desire health in disease, or freedom in imprisonment, than we now do bodies incorruptible as diamonds, or the wings of birds to fly with.
- Frederick William ordered Fritz to undergo a minimal education, live a simple Protestant lifestyle, and focus on the Army and statesmanship as he had. However, the intellectual Fritz was more interested in music, books and French culture, which were forbidden by his father as decadent and unmanly.
- At age 16, Frederick seems to have embarked upon a youthful affair with Peter Karl Christoph von Keith, a 17-year-old page of his father.
- After the prince [Frederick II, better known as Frederick the Great] attempted to flee to England with his tutor, Hans Hermann von Katte, the enraged King [Frederick William I of Prussia] had Katte beheaded before the eyes of the prince, who himself was court-martialled.
- Frederick William had his son married to Princess Elisabeth Christine of Brunswick-Wolfenbüttel-Bevern, whom Frederick despised, but then grudgingly allowed him to indulge in his musical and literary interests again.