A gigantic piece of artillery located in the center of the Muunilinst city of Harnaidan, the Harnaidan defensive cannon was used by the InterGalactic Banking Clan to protect their headquarters.
During the Battle of Muunilinst, the cannon's constant bombardment wreaked havoc on the Republic forces attempting to take the city, necessitating the use of ARC troopers to destroy it.
After working their way through the city, the ARC trooper squad planted a number of explosive charges on the cannon, successfully blowing it up. However, this action led the Banking Clan commanders to believe that the Republic artillery units were responsible, and that they constituted a larger threat than previously thought. With the focus being on these vehicles, the ARC squad could position itself on top of the headquarters, undetected.