Leonel's approach to war hadn't changed much over the years, only because he never officially learned battle tactics. What he was good at was understanding people and guessing how they would react before even they were aware.
In a situation like this one, where he had limited understanding of the parties involved and the environments the battle would take place on, relying on cleverness was a hard pass.
Rather than spending time wracking his brain to find clever schemes, the best path forward was absolute power.
But that was a problem in and of itself.
Not only was his power limited due to the Regulator, even if it wasn't, he didn't have the luxury of just suddenly going all out to defend the Sea Gods, because that would expose him much earlier than he wanted.