The Alternate History: HMS Invincible was always a busy girl. Soon after completion, she was constantly in and out of the dockyard; mostly to iron out all the bugs in the new 16” turrets. Once these and a few propulsion plant vibration issues were solved, she became the proud flagship of the battlecruiser fleet. After a few show-the-flag cruises, she returned to John Brown on the Clydesbank for a mid 1930’s refit. The well worn propulsion plant was renovated, her four single 4.7” anti-aircraft guns replaced by four twin units with accompanying high angle directors. An additional pair of 40mm pom-poms were fitted, along with several .5” machine guns. She patrolled with HMS Hood during the Spanish civil war and was in dockyard hands for a slight update, mostly radar installations, when World War 2 broke out. After searching for German surface raiders in the South Atlantic, she joined Admiral Cunningham’s Force H in the Mediterranean. It was an active period involving many Malta resupply runs. On these she was usually detached, with HMS Renown, to interdiction and harass the Italian Navy; unfortunately, no decisive engagements offered … the Italians being very cautious and reluctant to commit their forces. In May of ‘41, the German battleship Bismarck sunk HMS Hood. Hood was an old lady, but she was still “The Lady”, and this German victory resulted in a mad scramble of British forces to hunt her down. Invincible and Renown, again sent ahead of Force H, managed to intercept the battleship and cruiser Prinz Eugen just outside of German air cover and send them to the bottom. Back with the Home Fleet, the next year was of little activity, lying in wait against the possible sorties of German heavy units from Norway. Once new units of the Lion class became available, Invincible sped across the Atlantic for a refit in the USA. Here she got eight US pattern quad 40mm Bofors, along with numerous 20mm single mounts. The last two years of the war was spent with her wartime partner Renown, raiding across the Indian ocean and bombarding the Japanese home islands. She was in Tokyo bay for the Japanese surrender. Thoroughly worn out by seven years of war, HMS Invincible was sold for breaking up in 1949.

Reality: Towards the end of World War One, the US Navy started an ambitious naval program. Congress authorized the construction of 9 super-ships .. five battleships and four battlecruisers (the first of the type ever designed for the US Navy). The battleships of the South Dakota class were to carry a dozen 16” rifles in four triple turrets on a hull displacing 41000 tons and capable of 23 knots. The battlecruisers were, arguably, even more interesting. On an immense hull 888ft long, the 37000 ton vessels sported eight 16” rifles carried at the very impressive speed of 33 knots. They were, however, rather lightly armored with only an 7 - 8” main belt and a deck of only 2”. The gigantic scout cruisers had a very elegant look to them.

Japan, meanwhile, had started it's own naval construction program. Eight battleships and eight battlecruisers were designed and to be built, like the US ships, to give the their navy a qualitative edge over all others. The first batch were designed for 16” cannons, the last batch (the battleships at least) were to sport 18” guns.

The British, coming out of World War One, were sitting pretty good in numbers of capital ships compared to any other navy. The Grand Fleet had 42 capitol ships on hand. Unfortunately, the numbers didn't tell the whole story. Many of the ships were old, pre-WW1, and were being sold off for scrapping. Another, HMS Canada, was being sold back to Chile (having been building in British shipyards and then purchased from from Chile on the outbreak of WW1). It was in this atmosphere that the British became aware of the shipbuilding programs of the US and Japan. Not to be left behind in the technology race, they began designing the ships to outclass the ships being designed to outclass all others.

Several designs were drawn up for each of the battlecruiser (labeled K thru G) and battleship (labeled L thru N). The final designs ended up being similar in appearance, with two turrets forward and one aft of the tower-style bridge. This somewhat odd arrangement was chosen to reduce the length of the armored citadel required to protect the magazines. The final battleship sported 9 -18” rifles moving at 23kts. But it was the final battlecruiser design, labeled G3, that really shined. Here, E.L. Atwood and Stanley Goodall designed the most powerful British capital ship ever. A fine hull 856ft long housed nine 16” cannon, and 160000shp moved her along at 32kts. Armor was developed under the “all or nothing” scheme developed by the US in the Nevada class. This eschewed armor everywhere, and instead concentrated on having the maximum armor possible where it mattered. In this case the armor belt, carried internal to the hull, was 14” while the deck over the magazines was 8” thick. This vessel would have been comparable to anything built by any nation 20 years later.

But it was not to be. The Americans, seeing the new developments across both oceans, now realized their immense monsters then building would be outclassed before they were finished. Also realizing that they had started a new arms race, a very costly one at that, they were quick to try to tame the beast. They called together Britain, Japan, Italy, and France to talk arms reduction. The final outcome, after much delegation, saw Britain accepting parity with the USA as far as tonnage, and Japan agreeing to 60% of that total … a 5-5-3 ratio. Italy and France came out with less, so a 5-5-3-1.75-1.75 ratio in total.

All the new monsters then building, laid down, or designed, were stopped and scrapped. There was to be a 10 year moratorium on new construction, and a 35000 ton size limit after that. There were a couple of exceptions. The USA and Japan were allowed to keep two of the more advanced ships under construction, albeit converted to aircraft carriers. Hence the creation of the carriers Lexington, Saratoga, Akagi, and Kaga. As far as battleships, the USA were allowed to keep the units of the Colorado class, and Japan Nagato and Mutsu … battleships all carrying 16” cannon. As Britain had no such beasts, they were allowed to build two new units with 16” guns, but conforming to the 35000 ton rule.

So in effect the G3's got a new lease on life, but in a highly modified form. The propulsion plant was drastically cut, and weight saving measures were employed to get under the 35000 ton limit. They were, essentially, a 23 knot version of the G3 battlecruisers.