According to Greene and Armstrong, some planners assert adhering to the fundamental principles guarantees victory, while others claim war is unpredictable and the strategist must be flexible. Others argue predictability could be increased if the protagonists were to view the situation from the other sides in a conflict. Field Marshal Count Helmuth von Moltke expressed strategy as a system of "ad hoc expedients" by which a general must take action while under pressure. These underlying principles of strategy have survived relatively unscathed as the technology of warfare has developed.