Assertion: mm mortar | /r/HasProperty | an artillery weapon
Facets:
Source sentences:
text: The 320 mm Type 98 mortar (Japanese: 九八式臼砲, Hepburn: kyūhachi-shiki-kyūhō, literally "nine eight type mortar"), known by the nickname "Ghost rockets", was an artillery weapon used by the Japanese military during World War II, especially during the Battle of Iwo Jima.