Giam Loc

The old chronicles say

The texts closest in time to the Qin say exactly one thing about his canal: a canal was cut to open a grain road. Not one of them mentions a sluice gate, a stone channel, or where the cutting ran from and to. What stands out in the fullest of them is the price of the digging: the Qin had gone three years without unfastening their armour or letting a crossbow go slack, the grain still could not get through, and soldiers had to be pulled out of the deployment to do earthwork. In the old texts the canal is an emergency measure, not a work of engineering.¹

How later ages remembered

The notes to the Complete Annals, by contrast, describe the canal in close detail: stones laid to make a channel, the river water led into it, thirty-six sluice gates set along it; a boat entering a gate had that sluice shut behind it until the water rose, and so it could climb the rapids and run down the falls, and boats could pass between north and south. It is a fine description, concrete enough to be read as an eyewitness account of the work under the Qin.⁴

But it is not a description of the canal under the Qin. Follow it back and the passage comes from the Linh ngoai dai dap, written by a Song official in 1178 — some fourteen centuries after the war. What it describes is the canal of the Song, after later ages had dug it further, banked it and fitted it with gates. The canal therefore follows the same pattern as the rest of this war: each century adds a layer, and what is left in the end is not the battle but a line of water still in use.⁵