Diamond layout and the value of broad firing arcs

The diamond layout placed one heavy gun forward, one aft, and one on each side. This earlier arrangement differed from later wing turrets, whose firing arcs and structural complications became harder to justify as battleships and fire control changed. Imperieuse belonged to a period when ships were expected to fight at comparatively short range, so all-round fire remained useful. With modest manoeuvring, about three of the four 9.2-inch guns could bear across most approaches. Their separation also reduced the chance that one hit would disable the whole main battery.