The Zara class gained substantial armour over the Trento class, but retained a strong speed priority. Holding roughly 32 knots helped reduce the contemplated belt from almost eight inches to 5.9 inches before the machinery compromise was even considered. The change from four shafts to two meant that a single torpedo hit on Pola could disable all propulsion. For a cruiser that cannot carry battleship-scale protection, separated boiler and engine groups can offer more practical protection than armour alone.
Notable Point · 1:02:42-1:09:27
Zara's armour did not guarantee survivability
The Zara-class attempt to create a tougher cruiser sacrificed propulsion redundancy that mattered at Cape Matapan.