3 ships full of soldiers -- to conquer an entire planet, in the heart of the Federation?
Let's say all the Spock hologram smokescreen worked as intended. Then it would be what? 2000 soldiers against one planetful of half stubborn pacifists (it would go like "you are conquered!" "no I'm not" much like Spock's "since you will kill us anyway I choose not to cooperate"), half lirpa yielding crazy ponfarring green blooded hobgoblins.
And those flimsy invader ships blew up with one shot each from the warbird. The only way that invasion would last more than a few minutes is if the entire planet Vulcan has not one defensive weapon.
Probably they don't sice they are pacifists, so there is no gun to seize and defend the new romulan colony from the Federation counter attack.
Good going, Sela.