Mogador carried 138.6 mm guns, a calibre equivalent to about 5.46 inches. The earlier 1929 weapon had already appeared on the Le Fantasque class, while Mogador used a 1934 version. Developing this unusual calibre added another specialised system to a destroyer programme already built around extreme performance. A conventional 127 mm or 5-inch weapon would have avoided that extra design burden.
Notable Point · 43:28-45:32
Mogador's 138.6 mm gun adds another design complication
The 138.6 mm main battery added a specialised gun calibre to a destroyer already burdened by demanding speed and torpedo requirements.