Today’s object is a curious one that I have not been able to date accurately yet. It might be wartime, or it might date from the immediate post war period- if you can help tie down the date any more accurately, please comment below!
Today we are looking at a small bag, used for the carrying of books for the military. It is made of white canvas and is approximately 18″x24″ in size:

The instructions on how to return the empty sack are stencilled in black ink on both sides:

My thanks go to Andrew Spiesz who found this solitary reference in the front of an old pamphlet which indicated that the sack probably contained official publications, rather than fiction for the troops to read:

It would seem therefore that the sack was packed with official pamphlets and books, the top sealed and then it was dispatched to wherever had ordered books, either by rail, sea or air.