Live and let live is the spontaneous rise of non-aggressive co-operative behaviour that developed during the First World War particularly during prolonged periods of Trench Warfare

Trench warfare

Trench warfare is a form of occupied fighting lines, consisting largely of trenches, in which troops are largely immune to the enemy's small arms fire and are substantially sheltered from artillery...

 on the Western Front

Western Front (World War I)

Following the outbreak of World War I in 1914, the German Army opened the Western Front by first invading Luxembourg and Belgium, then gaining military control of important industrial regions in France. The tide of the advance was dramatically turned with the Battle of the Marne...

. Perhaps one of the most famous examples of this is the Christmas Truce

Christmas truce

Christmas truce was a series of widespread unofficial ceasefires that took place along the Western Front around Christmas of 1914, during the First World War...

 of 1914.

It is a process that can be characterised as the deliberate abstaining from the use of violence during war. Sometimes it can take the form of overt truces or pacts negotiated locally by soldiers.