However, since the other party has brought it up, they naturally intend to ensure its success. If I refuse, then I'm afraid our cooperation will also come to an end here.
A Mirror of Thousand Miles would certainly improve my own, or even my flagship's command capacity, but to rely on this alone to reverse the disadvantage in the confrontation with Katharina, would still be insufficient.
But the opening of the port is no small matter either, which inherently means that I cannot attack the incoming and outgoing merchant ships. This implies that this long-sealed land will henceforth open its doors, exchange resources, and foreign merchant ships will continuously come and go here, essentially exposing my base to everyone.
Mattdam is only 300 miles from Rhode Island and can be reached in a day and a night. If I set sail on a fair morning with favorable winds and tides, I could arrive by dusk.