Wiped Out
The only reason why Henry had decided to pay attention to the sea race was simply because the sea monsters were actually the most dominant race in this world at the moment.
If he wanted to conquer this world, he would have to deal with the sea race at the end of it all. And since currently, only two continents were left, with one of them already in the process of being conquered, then, Henry decided to personally deal with the sea race.
It was clear that sea monsters had somehow received information about what was happening on the surface. After all, it was only after several continents had been conquered by the human race that finally, the sea monsters decided to attack.
But in any case, Henry was not afraid of the sea monsters, despite the fact that they were the strongest force within this world. In any case, with his own strength, he definitely believed that he was capable of dealing with the sea race.