In the west Shanxi was threatened, as were the Chi and the Liao in the east. In 1548, the first raids were made. In 1549, Weng Wan Da proposed more walls. Costs for this project were estimated at 567,580 ounces of silver and would take 70,000 men 152 days to build. The plan was approved.
In the middle of the year, however, Weng became Minister of War, a position he held for a short while until his father died. Despite his support for wall building, Weng did not believe this would end Ming problems with the nomads. On the contrary, he advocated trade and diplomatic relations as the sole long-term solution. Unfortunately, the same rivalries that had crippled Ming decision-making in earlier times, crippled it again and the necessary steps towards conciliation were not made. Although the [M 002 / Ming defense lines] are often considered brilliant, it is also generally acknowledged that they overlooked a vital consideration - the ability of the nomads to find ways around them.
