This is partial text from the full article (usually with photos) at https://armorama.com/news/gb-modelli-bombarda-italiana-with-trench
Looks interesting. Is it WW I?
Heres a Wiki article on it.
Yes yes I know wikipedia isn’t a reliable source…
Good find, but the gun in question a little bigger. 58mm vs. 400mm. Or in your terms
2.3 in. vs. 15.7 in.