i was watching a segment about a film set during the chinese civil war. the segment shows a battle between nationalist and communist forces. whil i was watching i noticed that the communist forces were using a very unusual form of artillery. for some reason, they were using metal barrels dug into the earth at an angle and filled with potato sacks that contained some sort of explosive. they then fired the barrels using a rope fuse. they reminded me of early gunpowder cannons. im not sure why they did this. are there any cases of this happening in real life, and if so why? are the soldiers in this particular engagement simply short of artillery pieces?