Article 19: stopping a clean-slate rebuild

Article 19 tied new construction to allowed tonnage and ships reaching their specified replacement age. This prevented a signatory from discarding its legacy fleet wholesale and re-equipping with 1930 technology under the cover of replacement. Britain still had C- and D-class cruisers, the United States retained the Omaha class, and Japan carried older ships such as the Furutaka class. That inherited Japanese fleet also helps explain the Mogami design's original battery of five triple 6-inch turrets. Each navy kept its unequal mixture of old and new ships instead of receiving a fresh start. The treaty controlled the timing of replacement as well as total tonnage.