Old pack howitzer probably left over from the days of the French occupation. The VC kept it in a cave in the mountains and every day or two wheeled it out and popped off a few rounds at the Marines stationed at Camp Carroll. After a while the Marines figured out what was making the noise and decided to do something. They sent two rifle companies and an air strike to settle the problem. Then they carried it back to Camp Carroll for a display. Gotta love the USMC.