Naval power was very emphasized. They developed a very effective underwater mine/grenade. The prototype couldn't have any oxygen, so they changed it to have a snorkel made of intestines (with duck feathers on top for disguise). A line was attached to the sea mine for detonation. I can't speak to what ground troops would use, but the folks at Chinesehistoryforum.com have a sub dedicated to military tactics/weaponry you could benefit from.