Novel? Hardly. I've copied a Di Vinci sketch of Mortar siege usage that is in the collection of the British Royal family. The siege of Sebastapol in 1858 was the largest usage of the Mortar up until the U.S. Civil War. This particular mention was a first for the particular engagement, and is mentioned as such.
The other usages you state are in other posts on this topic, research of which leads me to say that the large Mortars were the decisive weapon of the conflict, particularly when given the mobility of a shipboard mount.