Battlecruiser classification depends on design purpose as well as protection. The terminology used here distinguishes early British two-word battle cruisers, such as the Invincible and Indefatigable classes, from more heavily protected one-word battlecruisers. The former specialised in economic warfare and scouting; German designs also needed to support the battle line because they might have to fight past the Royal Navy. The proposed Lexington class supplies another example of the economic-warfare type. Protective clothing provides an analogy for increasing coverage along the spectrum towards fast battleships and full battleships. A thick belt does not reveal how much of the hull is protected or what lies behind the armour. Bulkheads, subdivision, and systems that limit flooding determine whether protection works as a complete scheme.
Notable Point · 30:28-34:10
Purpose and armour place ships on a battlecruiser spectrum
British economic-warfare battle cruisers are distinguished from German designs intended to support the battle line, then armour coverage and subdivision show why one thickness figure is insufficient.