When we speak of Mr. McKinley's Navy, we have to begin somewhere and generally that is supposed to be with the SS Virginius Affair and proceed from there.
The conventional wisdom is that it was the humiliation that the US suffered having to follow in the bow wake of the powerful British who threatened Spain with war over the affair. The 53 Americans and British
fillibusters the Spanish executed for their alleged attempt to overthrow the Spanish administration in Cuba was the proximate cause for war, and the humiliation was the realization that the US Navy and Army was too feeble to do anything about it.
It was remarkable that the Johnson Administration had so scrapped the fleet and so allowed the shore establishment to run down that the Grant administration which followed it was unable to do anything but conform to British diktats (moreso than Spain) about the episode.
However, the real beginnings for Mr. McKinley's Navy have to be seen earlier and later than the SS Virginius, and it has to be rooted in more causes than just colliding American and Spanish interests in the Caribbean-> especially if the causes are to be tweaked into a slightly different outcome.
Once again we must look to SPAIN as the first enemy and this cause.
The bombardment of Valpariso was something American political leaders had to consider.
If that lesson needed to be reinforced,
the bombardment of Alexandria, Egypt and
the battle of Fuzhou drove home the reality that American leaders (presidents) faced in the late 19th century. From Grant forward, they wanted a powerful navy to defend the Atlantic ports from European strategic blackmail, but not until
Cleveland's first administration was a serious attempt to actually address the peculiar and uniquely American defense issues taken in hand.
Not only was the political climate suitable as the SS Virginius affair still rankled deeply with each new outrage that Spain perpetrated in "American" waters, but the technological chaos that became evident with the Franco Prussian War and which continued with the naval side-shows and demonstrations since thereafter (the heyday of Franco-British "gunboat diplomacy") when the lesser third tier powers (of which the United States was one) could expect an Anglo French allied fleet to show up and tell the local government to behave or see a seaport shelled into ruins, finally settled down to something stable.
That technological chaos was based on two fundamental factors; manufacture of good steel armored plate, and the manufacture of the built up hooped breech loading guns to throw explosive projectiles between 6 and 15 kilometers. The other ancillaries, such as automated computing and fire director systems to support such armored guns either ashore or afloat, and the steam, hydraulic, electrical, or internal combustion engines to move that armored artillery made their ancillary appearances, but that was the fundamental two factors practical solved that settled down by 1885. Railroad guns and the primarily steam engine propelled armored warship became well defined enough in technology plateau limits internationally, that the Americans could finally be confident that they could meet it with their native resources.
The "excuse" was to make the US coasts secure against second-rate powers like Spain. That would be the bill of deceitful goods sold to an isolationist Congress. The real dream though, was to remove the humiliation of ever seeing another American commodore helpless to intervene as the US Mediterranean squadron was when the French and the British shelled not only Egyptian interests, but American and Italian interests and PROPERTY and CITIZENS in Alexandria, Egypt as well as in Chinese ports in the Pacific.
Coastal forts would stand the European interlopers offshore, but to protect Americans overseas, the US would need a very strong navy.
And that leads to a curiosity. America in the age of sail, could get away with lease basing and relying on foreign ports for their frigate/sail cruiser navy. It was not innate conservatism among American ship captains that made them reluctant to abandon sails as a propulsion system. The USN had no safe overseas bases to re-coal. Steam engine plants were weak and unreliable. The British had good steam engine plants and coaling stations everywhere. And they had a huge numbers advantage.
The French since their humiliation during the Franco Prussian War had decided to assuage their national humiliation by continuing Louis Napoleon's foreign policy of adventurism. Maybe France could not beat the Germans in Europe, but France could beat everyone else overseas (except the British) and thereby restore her tarnished glory that way?
I could point out that the Chinese had something to say about that in Indo-China, and that things did not go well for France in Japan, but for the most part, the French were right in the 1870s and 1880s and they were a primary cause of American concern and anger in the Pacific those decades as the French strongly interfered with American commercial exploration in Asian markets.
Not to say that the Americans were alone, but the British could do something about it (Suez Canal) and often did. Not until Mister McKinley's navy (the real one not this AU one) showed its teeth (Spanish American War) did the Panama Canal happen and the admirals in Paris finally read the {US) plot. They were through as a global navy.
The British would take longer, much longer.
But what about the Germans?
Well, they never got out there and developed the infrastructure or the practical means for a global navy. Not really. They; like the Italians and the Russians of the era, were a local regional power with a limited out of region overseas presence.
How does a navy with no overseas bases and coaling stations become a global navy and fight a global naval war?;
That is a good question for Grover Cleveland's Secretary of the Navy
William Collins Whitney.
And one we will explore in the AU. You already see some early examples.