Defeat and merchant interests drove Song naval expansion

Early Song naval activity supported conquest but later lost priority, leaving many riverine units under provincial control. The unsuccessful 1077 campaign against Annam exposed the shortage of suitable vessels and encouraged both state shipbuilding and merchant contributions. Two coastal yards were ordered to build 600 ships each year, while yards in Hunan received orders for another 300, yet officials still complained that many vessels were not seaworthy. Only after the fall of Northern Song did a durable sea-going imperial navy emerge.