The principles of war are appreciated as guidelines in doctrines and theorist Robert R. Leonhard states that surprise is more vital than ever in combat, but criticism is equally distributed. The principles might not even be valid since they lack examination systematically and empirically.  The purpose of this study is to examine the principle of surprise through a case study based upon naval operations during the Yom Kippur and Falklands War.  This tentative study is based on the thoughts of classical theorists. These thoughts are operationalized and subsequently investigated in literature in order to evaluate the validity.  The results show that the principle of surprise is valid to some extent in modern combat, but the factors validity may vary. The principle of surprise also becomes more nuanced in this study, as indicators and examples became connected to the principle.  It can be concluded that the study identifies a need for further empirical research as well as investigation on whether new factors can be discovered in modern combat.