Meaning of the legend?

There was a daimyo named Akechi Mitsuhide who built a castle on Mount Hiei. The Toyotomi attacked the castle and it could not be destroyed. They became very frustrated and went to a fisherman and found out where the castle’s water source came from. They cut off the water supply and many of Mitsuhide’s men committed suicide. On rainy nights, legend says large fire come from the castle to sink boats or set them off course. The spirit of Akechi does this to get even with fishermen that caused his tragic defeat.