I can't think of this being done anywhere before...
A lot gets made of what if the Spanish armada had been succesful including a hell of a lot of rubbish.
So WI...The English armada is succesful.
Everything was against it from the start really so it would require a lot of messing around prior to it being launched but WI the theory all proves sound- England seizes the Azores, starts off a massed war of independance in Portugal, destroys the remains of the Spanish warfleet and captures the treasure fleet.
And yes, its succeed. Woops.