Bag, american? Date and purpose please.

[ILH]

Hi,
Picked up this bag the other day. Purportedly it came from the estate of a 'British officer who served in Germany' and used for shotgun cartridges.
I think it is american and ww1 or earlier. The canvas was a green colour used up to the 1920s, the inside is blue-grey, and its stamped "citadel workshops, dept of stores (can't read the rest).
Anyone got any ideas?
Thanks.

[ILH]

More pictures

[Wagriff]

The stamp should read "citadel workshops, dept of stores Egyptian Army" and perhaps also have a date such as 1916 on it somewhere. I believe that this is a WWI Egyptian Army document dispatch case.

[ILH]

Excellent! Thankyou.