The Battle of Lin'an lasted for two full months, during which more than a month and a half was spent sweeping the uprisings across the major dimensions of Lin'an. After Lu Hong killed the Old Ancestor of Lin'an, within six days, the main force of Lin'an was completely routed.
However, defeating the main force of Lin'an did not mean capturing the entire Lin'an World.
During the subsequent time, the clean-up work was handed over to the Crown Prince's division to conduct investigations and clear-outs in places within the Lin'an World that might hide large remnants of enemy forces.
Such work was labor-intensive, and the casualty ratio was higher than in large-scale battles because you never knew how many enemies might be hidden in the mountain valleys or at what level their strength was.
