An American 18-inch gun program before the treaty era

Early American adoption of 18-inch guns would likely raise the treaty caliber ceiling and push Britain toward heavily armed fast battleships rather than lightly protected battlecruisers.

Question

What if Congress funded the United States Navy more generously in 1914 but demanded 18-inch guns to keep American battleships ahead?

Short answer

The treaty gun limit would probably rise to 18 inches, and Britain would likely answer with 18-inch fast battleships derived from its Admiral-class studies.

Notes

A funded American 18-inch program in 1914 would change the baseline from which every later navy negotiated. The Washington Naval Treaty would probably accept 18 inches as its maximum rather than forcing an established weapon backward. Britain could respond by turning Admiral-class studies into 18-inch fast battleships with useful armor and roughly 28-knot speed. The wider consequences are left open because the altered building programmes would produce many further changes. One congressional demand could therefore reshape both the ships built before the treaty and the treaty's definition of an acceptable capital ship.