The crossbow was one of the deadliest weapons used by individual soldiers in the history of warfare. During the Northern Sung (960-1126). most crossbows were quick-set bows equipped with stirrups, but perhaps the most powerful among them was the arbalest. In the Northern Sung, many soldiers were trained to use crossbows, but they were not concentrated into a single unit for warfare. In the early and middle Northern Sung, the training of crossbow specialists was of high priority, but later these soldiers received less training. Judging from Sung military history, the crossbow proved to be an extremely effective weapon in battles involving, for example, the defense of cities, offensive drives, and warfare in rough terrain. In fact, when crossbow archers fired together in rapid unison, their force was sufficient to halt advancing forces on horseback, even those heavily armored. However, in the Northern Sung, we find that the crossbow was not used to its fullest potential nor in the most advantageous situations. Towards the late Northern Sung, when political and military power eroded on the frontiers, few archers were trained to use crossbows. To make matters worse, Sung generals appeared to have had little experience in utilitizing crossbow archers during pitched combat with Chin soldiers on horseback. Thus, this may by one of the elements that led to the fall of the north in 1126.