What was the purpose of the satchels worn around the neck and on the chest of many Entente soldiers during WW1?

by WWIflyingace62

http://www.worldwar1.com/dbc/jpg/2dbstalk.jpg

Specifically, what were they used for and why worn in such a strange fashion?

lojafan

That is a gas mask bag. They wore it there because it gives access to it much quicker and easier, as well as being a holder for the filter canister.