The Gas Canister Deployment Strategy is a historical item which can be found by Emile in Ypres during Chapter 1.
Location[]
After escaping the falling bomb and gas to reach the next trench tunnels, look for this item near the entrance.
Description[]
"Gas canister deployment strategies were simple, but they did depend on the weather, especially on winds. Gas use required a constant downwind towards enemy lines, to avoid the gas returning to its sender. Any battle plans were therefore dependent on the weather forecast."