Answer: Very little movement of the line because of extremely high casualty rates.
Step-by-step explanation:
When the First World War broke out, both sides decided it best to try to outflank the other to enable them to surround and defeat the opponent. This resulted in what was called the 'Race to the Sea' as both sides engaged in flanking action till they reached the North Sea.
From here they dug in for a stalemate and thousands of miles of trenches were dug. Between the opposing trenches was an area known.as No Man's land and it was full of barbed wires and bomb made craters.
With each battle, soldiers would have to climb over the trench and into.no man's land to attack the enemy. As they did so they were mowed down by machine gun fire leading to high casualties and even if they did manage to reach the other's trench, the defenders would simply retreat to trenches behind them and the cycle would repeat itself.
Both sides kept doing this and for this reason there was very little movements and high Casualty rates.