Trench warfare
Trench warfare occurred when a revolution in firepower was not matched by similar advances in mobility, resulting in a grueling form of warfare in which the defender held the advantage. On the Western Front in 1914–1918, both sides constructed elaborate trench, underground, and dugout systems opposing each other along a front, protected from assault by barbed wire, mines, camouflaged trapping pits, and other obstacles. The area between opposing trench lines (known as "no man's land") was fully exposed to artillery fire from both sides. Attacks, even if successful, often sustained severe casualties.
Aisne
It is thought that the Aisne River was the birthplace of the trench warfare seen in the First World War. The British Expeditionary Force (BEF) had initial early successes driving the Germans back to the Aisne River; the German troops dug in and managed to hold out against both British and French attacks. This German entrenchment was to mould the entire face of World War One as both sides began digging in and fortifying their positions. Thus began the stalemate that became a significant feature of the First World War.This linguistic variance probably explains the difficulty for residents south of Aisne to identify themselves as belonging to the Picardy region.
In 2008, the department had 4.1% of second homes. This table shows the main communes of Aisne that have second homes which occasionally exceed 10% of total housing.