If men make war in slavish obedience to rules, they will fail.

Attributed to Ulysses S. Grant, the line argues that rigid, unthinking adherence to prescribed “rules” in warfare leads to defeat. Its force lies in contrasting obedience with judgment: rules can summarize past experience, but war is contingent—shaped by terrain, morale, logistics, and an adaptive enemy. The quote thus champions initiative, flexibility, and a commander’s responsibility to interpret principles rather than recite them. Read in a broader military-intellectual sense, it also critiques bureaucratic or doctrinaire systems that reward compliance over results, implying that effective action requires independent reasoning and the courage to depart from convention when circumstances demand it.