The First World War broke out in 1914 and Nash enlisted in the army later that year. He worked with the Home Service during the first London air raids and later trained as an officer.
In spring 1917 Nash arrived on the battlefields of the Ypres Salient in Northern France. Initially he wrote that he was as excited as a schoolboy and thought the landscape looked not unlike Sussex.
He was impressed by the powerful continuity of nature in the midst of the bombed and battered countryside. His early drawings used a bright, even colourful, palette and he painted natural scenes which appeared undisturbed by war. After only three months at the front Nash was injured after falling into a trench and invalided back to England. A week later his division was virtually annihilated in the infamous Battle of Hill 60.
During his leave, Nash exhibited some war drawings in London. The work was noticed by the War Artists Advisory Committee and when he returned to France later that year it was as an official war artist. He arrived in the aftermath of the Battle of Passchendaele, the blindest slaughter of a blind war, and his eyes were opened to the horrors of war. Nash continued to concentrate on landscape and his outrage at the waste of life was expressed through the violation of nature. He adopted the angular avant-garde styles of Cubism and Vorticism and produced powerful and confident landscapes that were both visionary and terrifyingly realistic.