The dadao (ta-tao; Chinese: 大刀; pinyin: dàdāo; Wade–Giles: ta4-tao1; literally "big knife") one of the varieties of dao or Chinese saber, is also known as the Chinese great sword.
Based on agricultural knives, dadao have broad blades generally between two and three feet long, long hilts meant for "hand and a half" or two-handed use, and generally a weight-forward balance. Some were made for military use, but they were most commonly associated with civilian militias or revolutionaries. While not a particularly sophisticated sword, the weight and balance of the dadao gave it considerable slashing and chopping power, making it an effective close combat weapon for untrained troops; it was used in this role as late as the 1930s in the Second Sino-Japanese War. During Operation Nekka the Chinese claim that whenever they had a chance for close engagement, the dadao was so deadly that they could cut off the heads of Japanese soldiers with ease. A military marching song, the Dadao March, was composed to become the rally cry for Chinese troops throughout the Second Sino-Japanese war to glorify the use of dadao during battle with the invaders.
In origin, design, and use, the dadao is broadly comparable to the European "Großes Messer" and falchion. However, the dadao was also commonly used by executioners for beheadings.