Armored Cruisers and the Washington Treaty

[Guinness]

So I've been puzzling over this for days, and gone over all my books looking for an answer, searched online, etc. Why did the USN get to keep its armored cruisers after the enactment of the Washington Naval treaty? It turns out the USN wasn't the only power that retained pre-WW1 armored cruisers.

To recap, Washington defined a capital ship this way in Part 4:

A capital ship, in the case of ships hereafter built, is defined as a vessel of war, not an aircraft carrier, whose displacement exceeds 10,000 tons (10,160 metric tons) standard displacement, or which carries a gun with a calibre exceeding 8 inches (203 millimetres) .

But the "hereafter" to me means it only applies to ships newly built, not those that already exist. It seems to me the definition didn't apply to armored cruisers.

The Washington treaty is also very explicit about listing ships which could be retained in Chapter II. For the USA, the list of ships which may be retained in Chapter II part 1 are: Maryland, California, Tennessee (the BB), Idaho, New Mexico, Mississippi, Arizona, Pennsylvania (the BB), Oklahoma, Nevada, New York, Texas, Arkansas,  Wyoming, Florida, Utah, North Dakota, and Delaware. It goes on to say "On the completion of the two ships of the West Virginia class and the scrapping of the North Dakota and Delaware". So no ACs listed.

Further down in Section II of the copy I'm looking at (https://www.loc.gov/law/help/us-treaties/bevans/m-ust000002-0351.pdf), there is also a scrapping schedule, and the ships the US is to scrap are listed (with their ages): Maine (20), Missouri (20), Virginia (17), Nebraska (17),Georgia (17), New Jersey (17), Rhode Island (17), Connecticut(17), Louisiana (17), Vermont (16), Kansas (16), Minnesota
(16), New Hampshire (IS), South Carolina (13), Michigan (13), Washington (0), South Dakota (0), Indiana (0), Montana (0), North Carolina (0), Iowa '(0), Massachusetts (0), Lexington (0), Constitution (0), Constellation (0), Saratoga (0), Ranger (0), United States (0). This goes on into later years detailing the replacement schedule. Again no ACs here.

The tables for the other signatories are similar: they all include both dreadnoughts and pre-dreadnoughts, but they don't include any Armored Cruisers, with one exception. One ship which could be considered an AC appears in this set of tables: The Japanese ship Ikoma. Ikoma and her sister Tsukuba had been reclassified by the IJN as Battlecruisers in 1912.

In many places one reads that Washington led to the scrapping of armored cruisers, but I'm not sure that's the case. The Treaty came into effect on August 17, 1923. HMS Minotaur was sold for scrap in March 1920 and her sister HMS Shannon paid off in May 1919 before finally being sold for scrap in December of 1922. HMS Achilles, the only surviving Warrior was sold for scrap in May 1921 after more than 2 years as a training ship. Every single one of the survivors of the earlier RN AC classes, clear back to Monmouth were scrapped no later than 1922. So for the RN at least, it seems that other factors led to their scrapping, not the treaty.

Many other ACs survived: The Japanese Kasugas continued in service through through World War II, and only became training ships in 1927. The French kept members of the Gloire and Léon Gambetta classes into the late 20s or early 30s, or even later. The Italians didn't seem to have any large cruisers before Washington. 

So it seems to me that while it may be true to say that Washington's terms meant that treaty cruisers succeeded armored cruisers in building programs, the contention that the treaty caused the scrapping of armored cruisers is entirely false.

[Desertfox]

The Ikomas had more in common with pre-dreadnoughts than with armored cruisers, so it makes perfect sense for them to be mention.