The replacement rules explain why fleets still carried visibly old ships in 1939. A treaty navy could no longer discard an ageing hull and order a successor solely because the ship looked obsolete. Legal eligibility followed completion dates, displacement categories, and the permitted lead time for laying down a replacement. The uneven appearance of interwar fleets therefore reflected the treaty timetable as well as technical age and national preference.
Notable Point · 7:31-8:46
Why obsolete-looking ships stayed in treaty fleets
Replacement restrictions explain why fleets still contained visibly outdated warships on the eve of the Second World War.