马当系长江中游的战略性咽喉之地,直接关系武汉的安危。会战准备阶段,本着“防守布置,力求精密”的要求,中国海军在江中设置了三层阻塞线,靠近江底的一层由一个个内装大石块的铅丝网沉江而成,有的还设法做了固定处置,各网之间还紧紧系在一起,形成一道水中暗墙。其上凿沉一些帆船,里面放上带有利钩并向上安放的铁锚或带锋利边沿的巨石,浅没于水 Madang Department of strategic throat in the middle reaches of the Yangtze River, a direct relationship between the safety of Wuhan. During the preparatory stage of the battle, in line with the requirements of “defensive arrangement and preciseness”, the Chinese Navy has set up three layers of blocking lines in the river. A layer near the bottom of the river consists of lead screens that contain large stones, Shen Jiang , And some managed to do a fixed disposal, the networks are also closely tied together to form a dark wall in the water. On which sinking some sailing, which placed on the hook with the hook up and placed iron anchor or sharp edges with boulders, shallow no water