This month sees the release of the paperback edition of Stephen Bull's fantastic volume 'Trench' . It's a detailed and comprehensive guide to a definitive aspect of fighting in World War I. In order to celebrate it, we're doing a little recognition test. We'll be giving away one free copy to one lucky winner!

As a youngster whose interest in military history was just beginning and who loved to draw, I used to try to design my own trench systems, rendered in coloured crayons. Sadly, I can't dig out any examples of these masterpieces to show you, but I can confirm they often featured such luxurious comforts as dug-in double beds, hot water taps and reinforced canteens serving three-course meals.

Of course I soon realised that life in the trenches was one of the most grim facets of World War I. 'Trench' certainly reinforces this point, but it also shows how complex the tactics and equipment particular to trench warfare became. Chapter 5 is entitled 'Gas', and explores this most terrifying weapon and the methods used to counteract it. Below is a colour plate from the chapter, showing 6 different types of Gas mask. We want you to identify the different types of mask, and email your answers to the [email protected] inbox!



Click on the image to go to our flickr site, where you should see numbers appearing under each mask when you hover over them. Use these to number your answers. We will accept answers until this Friday, and will pick one lucky winner from the entries!

If you are super clever, you might be able to track them down from a source quite close to home... but enough hinting! Get your answers in swiftly if you want to be in with a chance of winning a copy.

Good luck!