Ww1 trench maps why do some just have front line and then the German trenches but no detailed British trenches marked

[arantxa]

Thanks 

So to clarify the fermented trenches are well marked but there is just a line for the British which says front line ..who would use these 

[Hedley Malloch]

In case they fell into enemy hands. They were meant for British/Allied use only. 

[WhiteStarLine]

As Hedley says.  Ironically both sides looked to captured maps to get the best overview of their own trenches!  This is from 'Survey on the Western Front', page 37:

 

[chaz]

If you ever see WW2 series Band of Brothers, episode 2 Dick Winter is shown finding a German map at a gun emplacement. A bit further in the episode he is told the map has gone further up the command line , he is told done a good job. Likewise, I think on operation market garden, a German is seen looking through a crashed glider and finds maps and details of the first days of D Day.