Song maritime strength was chiefly economic and defensive. Its overseas political ambitions were modest, apart from the failed 1075-1077 expedition against Annam. Harbour works and trade policy encouraged overseas merchants, while convoy-escort units protected incoming and outgoing shipping. The contrast with later Mongol and Ming ambitions distinguishes a navy organized around commercial security from one intended for broad maritime expansion.
Chapter · 2:30:25-2:32:30
Song sea power grew from commerce and convoy protection
See why Song China developed sea power primarily to protect maritime trade rather than to pursue expansive overseas conquest.