What did the term billet mean in World War 1?
Billets were lodgings for soldiers.
A billet was an assigned place to sleep on base, usually in a barracks or onboard a ship. The British commonly billeted soldiers in the homes of the colonists. Off base, they have tents if they even get to stop long enough to sleep. Mostly they just sleep in the open or any cubby hole place they can find, sadly that is usually a trench.
The term is a Jamaican Patois abbreviation of the word bottom into batty. The term was brought to the United Kingdom by post-World War II Jamaican immigrants. The term was further popularised in the United Kingdom by the rise of British comedian Sacha Baron Cohen, and his portrayal of the character Ali G.