Upon the death of Vasily III's widow, Elena Glinskaya, he challenged the authority of Prince Ivan Belsky, procured his incarceration, married Anastasia of Kazan (Ivan III's granddaughter), and proclaimed himself regent for Vasily III's heir, the young Ivan IV, in 1538.
The book was based exclusively on Peersson's own experience and on the oral narratives by contemporary Russians (Vasily Shuysky, Maria Nagaya and the retinue of False Dmitriy I) and Western witnesses (Caspar Fiedler, Conrad Bussow).