Caissons

5 clues
Chests for ammunition
Watertight structures
Two-wheeled artillery wagons
Carriages used at presidential funerals
They went rolling along in old US Field Artillery song lyrics
Similar answers:
Achesons
Addisons
Ahamforallseasons
Alanparsons
Alisons
Allmysons
Amanforallseasons
Amanorforallseasons
Amanseasons
Ambersons
Americaisa
Ammanforallseasons
Andersons
Andthehendersons
Ansons
Apersonsneezing
Aprisonsail
Arsons
Ballisonstrike
Baseballseasons