Piracy was a major reason for sustained naval investment, so the fleet had routine work beyond climactic battles. Maritime rivals and neighbouring states, including the Southern Tang and Southern Han, also made naval capability strategically necessary. Against the Mongols, ships allowed Song forces to move around land armies and counterbalance their advantages on several occasions. These continuing duties helped justify maintaining a large navy.
Notable Point · 51:11-51:49
Why the Song kept such a large navy
The standing navy served anti-piracy and regional-war needs while giving the Song a maritime way to manoeuvre around Mongol land power.