Answer:

caissons

Answer	Crossword Clue
CAISSONS	Watertight structures
CAISSONS	Ammunition chests
CAISSONS	Two-wheeled artillery wagons

CAISSONS	They went rolling along in old US Field Artillery song lyrics
CAISSONS	Chests for holding ammunition.
CAISSONS	Chests for ammunition
CAISSONS	Carriages used at presidential funerals