Field-Marshal Sir Douglas Haig is the best-known (if popularly reviled) British commander of the First World War. But several important periods of his career remain poorly understood. This article aims to refocus attention on one such period: his command of First Army during 1915. After looking at the creation of armies within the British Expeditionary Force in December 1914, the article examines the relationship between Haig and the Commander-in-Chief, Sir John French, and highlights the unprecedented degree of independence that Haig was allowed during that year. This had a number of important implications for the offensives the British conducted during 1915, which were fought according to Haig's unrealistic prewar ideas of the "decisive" battle and the "human-battlefield."