1930 London Naval Treaty: An Introduction Part 5 of 5/Articles 17-22

Article 17 permitted limited tonnage transfers, while Article 18 scheduled America's final heavy cruisers and offered a light-cruiser substitution that clashed with US Pacific priorities.

A light-cruiser comparison turns treaty tonnage into a practical design question: more hulls, more protection, or a different turret layout.

Article 19 limited replacement construction so ageing ships could not become an excuse for an immediate modern rebuilding race.

Article 20's bespoke British and Japanese allowances reveal how much national bargaining was hidden inside a common treaty framework.

The treaty may have offered Japanese civilian leaders a way to restrain defence spending, though domestic opposition made that a dangerous gamble.

Article 21 gave treaty powers a route to raise their own limits if another power's construction changed the security balance.

Despite Japanese opposition and later false displacement claims, the treaty restrained naval decisions for several years.

Article 22 applied prize-rule safeguards to submarines, requiring the safety of passengers, crew and papers before a merchant ship could be sunk.

Roman grain routes and Napoleonic transport illustrate why merchant ships were strategic infrastructure to capture and reuse, not merely targets to destroy.

Prize law assumed room for captured crews and access to a friendly port, two requirements that worked badly for Central Powers submarines in the Atlantic.

The World Disarmament Conference spent years trying to extend naval arms-control success to land and air forces but produced no comparable treaty.

A cruiser or fortress can defend one state's strategy while enabling pressure against another, making simple disarmament categories politically unstable.

A fortress threatens an invader's rear and lets a defender hold important ground with fewer troops, freeing mobile forces for operations elsewhere.

Roads, beach works, artillery positions, suitable ammunition and guarded reservoirs show how local infrastructure could have complicated the defence of Singapore.

The Second London Naval Treaty entered a deteriorating political environment and contained escape clauses that weakened its limits from the outset.

A hypothetical three-triple 15-inch armament exposes how treaty limits, shell logistics and inherited British turret engineering shaped the King George V class.

Carrier aviation was advancing in 1930, but the treaty mostly repeated Washington rules because no navy yet wanted close limits on an unsettled field.

American dive-bombing and British-Japanese torpedo-aircraft development show why 1930 carrier rules would have constrained technologies still moving in different directions.

Sea-search radar kept the slow Swordfish useful on patrol against submarines that still spent much of their time on the surface.