English common law jurists in the Middle Ages and early modern times viewed loyalty exclusively as a phenomenon based on a deeply personalized connection between a vassal and his primary lord-king. It was in this form that the idea of loyalty reflected the traditional feudal principle demonstrating the connection of loyalty and its main attribute, fidelity, with the so-called cause of the king. Despite its ubiquity and related practices, this understanding of loyalty to some extent competed with the gaining popularity view of the applicability of the principle of loyalty and related behavioral stereotypes to such concepts as kingship and the community of the kingdom, including their territorial dimension. The article deals separately with the phenomenon of so-called dual loyalty, the origins of which are linked to the so-called right of fiefs and the practice of subfeudation. This form of loyalty and related subjection allowed for the simultaneous association of a person with two monarchs, as well as the practice of land ownership in two contiguous kingdoms. The author examines how such a form of loyalty was positioned in the right-wing literature of the 15th — 17th centuries, emphasizes the legitimate nature of this phenomenon, and considers the cases that led to its termination.