https://commons.wikimedia.org/wiki/File:Trench_Warfare.png
Below is a video from the outstanding The Great War series on YouTube taking a detailed look at trench warfare.
https://www.youtube.com/watch?v=P92guhd7d-8
History Channel - Life in the trenches
This website from the trustworthy History channel website provides a good overview of trench warfare, key facts and also includes videos. Click here to visit this website.
The Imperial Museum
Get an overview of trench warfare by visiting this page from the Imperial Museum's website. It includes original photographs, videos and links for further research.
Ten things that could save your life in the trenches is an article from the British Imperial Museum that examines crucial items essential for life in the trenches.