Dahlgren gun
Dahlgren gun is a naval artillery or rifled muzzle loader.
Overview
American naval artillery family.
In detail
It is associated with United States.
Sources
Each source is named with the standing the house places on it, so the evidence can be weighed rather than taken on trust.
reference work · Reputable secondary · Wikipedia
“Dahlgren gun”, English Wikipedia, consulted as further reading
Consult the sourcereference work · Reputable secondary · Wikidata
Wikidata, structured authority record Q1157449: Dahlgren gun
Consult the source