This article presents the first reassessment of the strategic rationality and credibility of French nuclear weapons policy before 1974. Building on untapped primary material from across the world as well as technical analysis, it shows that early Cold War French nuclear weapon procurement and deployment are incompatible with a precise grand design and the requirements of strategic rationality. The first generation of French nuclear forces also lacked technical credibility, despite reliance on outside help. Several French officials knew about it, as did their allies and adversaries. These findings de-exceptionalise French nuclear history and challenge conventional wisdom about Cold War nuclear history.