The average distance between the front line trench and that of the enemy was 250 yards and for the newly arrived British Tommy it was a place of fear and uncertainty.

The trenches of the time were roughly seven feet wide at the top, three feet wide at the bottom and roughly seven feet deep.  The trenches were largely open to the elements, though by 1916 some support and reserve trenches were covered with corrugated iron or wood to provide a degree of protection. 

For every mile of front there would be up to 30 miles of trenches arranged into a front line, a support line and a reserve line, all linked by a network of communications trenches. 

To minimise the effects of blast from shells or machine-gun fire the trenches could not be dug in straight lines, but were dug in a series of right angled sections with each section about fifteen feet long. 
 
However, during times of heavy fighting, the front line would degenerate into nothing more than an uneven line of muddy holes. 

Perhaps the most dangerous part of the lines was the ‘saps’.  These ran out into No Man’s Land at right angles from the front line trench and were used both as listening posts and to launch forays on the opposing lines.