C137 The son should be like the sun

Ziling, also known as Nanjing, was a place where war had been fought since ancient times.

Why was it so important? They had to start from the topography. Nanjing's flat area was located north to south long, narrow to the east and west, with a straight line between north and south, and a distance of 150 km. The width of the east and west was 50 to 70 km in the middle