Yamatos and Iowas joining the 1915 Home Fleet

What if Yamatos and Iowas joined the British Home Fleet in 1915?

They would devastate the German fleet and spur Britain to build still larger ships, disrupting the entire later treaty framework.

Two Yamatos and four Iowas bring heavy guns, speed, and radar-directed fire control into a fleet still fighting with First World War sensors and doctrine. The speakers expect them to overwhelm the High Seas Fleet at ranges where German ships cannot reply effectively. Their arrival also creates an immediate basing, ammunition, fuel, and maintenance problem for Britain and Japan because 1915 infrastructure was not built for them. Britain would unpause gun, armour, dockyard, and design expansion and pursue still larger capital ships in response. A later Washington-style treaty becomes exceptionally difficult once several navies possess ships far beyond the historical starting point.