The War didn't end within the time scale both countries had hoped. The front lines were a meat grinder.
War had its ways to destroy the foolish and the naive. Many foundation establishment state or lower cultivators had died by slashing yang stone grenades with their swords. They would slowly burn to death in front of the horrified eyes of their comrades. Some would survive, with terrible burn scars covering their body. They would need an incredible amount of resources and time to fully heal, putting them out of the war effort permanently.
Sects would receive a psychological shock after seeing these once dashing and handsome older martial brothers with melted skin, dull and white eyes that don't see, wheezing, and struggling to breathe through intact parts of their lungs.
Gone were days the martial heroes valiantly sweeping through the battlefield.