Post History

My SO and I were discussing the following sentence in his writing: 

 > This is the tale how once the Septemi helped King Nicodemus subdue walking firestorms, how we hunted cultists and mongrelfolk in the empire, how we built an imperial legacy, how we were betrayed and brought to ruin.

"The tale how" hurts my ear, but I can't say exactly what is wrong with it - it doesn't seem grammatically incorrect (though I'm no expert). Is "the tale _of_" simply idiomatic, or is something more fundamental going on here?