Every military district had its own special forces. Normally, they would be the ones who would see blood. The other soldiers would usually never do such a thing until they retired from the military.
The reason why they didn't choose new recruits from the special forces was because as the management of the various mechanisms in the country became more and more mature, they wouldn't have a certain amount of space to move around like in the past. If they suddenly chose one or two clueless individuals from the special forces, although these people were powerful, their departure would have a greater impact on the original military unit. Hence, the military decided that this batch of recruits wouldn't be selected from the special forces like before. Instead, they would choose the top soldiers from the various military districts.
