The First Army was part of the British Army during the First World War and was formed on 26 December 1914 when the corps of the British Expeditionary Force were divided into the First Army under Lieutenant-General Sir Douglas Haig and the Second Army under Horace Smith-Dorrien. First Army had the Ist, IVth and the Indian Corps under command. The First Army suffered reverses at Vimy Ridge in May 1916 and at Fromelles the following month. From 1917, the First Army also included the Portuguese Expeditionary Corps. The First Army took part in the 1918 offensive that drove the Germans back and virtually ended the war.