From 1544 to 1549, Weng Wanda (翁萬達; 1498-1552) embarked on a defensive building program on a scale unprecedented in Chinese history. Troops were re-deployed along the outer line, new walls and beacon towers were constructed, and fortifications were restored and extended along both lines. Firearms and artillery were mounted on the walls and towers during this time, for both defence and signalling purposes. The project's completion was announced in the sixth month of 1548. At its height, the Xuan-Da portion of the Great Wall totalled about of wall, with some sections being doubled-up with two lines of wall, some tripled or even quadrupled. The outer frontier was now protected by a wall called the outer border (外邊, wàibiān) that extended from the Yellow River's edge at the Piantou Pass (偏頭關) along the Inner Mongolia border with Shanxi into Hebei province; the inner border wall (內邊, nèibiān) ran southeast from Piantou Pass for some , ending at the Pingxing Pass; a river wall (河邊, hébiān) also ran from the Piantou Pass and followed the Yellow River southwards for about .