C1480 How about It be a Naval Cannon

Qin Guan knew that in that parallel period of history, it was Dr. Boole who brought up the 203 mm caliber cannon for the country.

Actually, in the era of battleships, this caliber was the most common type of cannon. However, cannon technology was constantly developing. The current 155mm howitzer could shoot 40 kilometers, what about in the past? In the era of battleships