Battle of Ypres in October 1914. Appointed a Companion of the Order of the Bath on 18 February 1915, he also led the Brigade at the Battle of Festubert in May 1915. Cavan was promoted to major general and given command of the 50th (Northumbrian) Division on 29 June 1915; a mere two months later he was appointed the first commander of the Guards Division and, having been appointed Commander of the French Legion of Honour on 10 September 1915, he led his Division at the Battle of Loos later that month. He was elected a representative peer from Ireland on 24 September 1915 and as such was one of the last to be so elected before the creation of the Irish Free State. In his role as Commander of the Guards Division he informed Major Winston Churchill of the latter's attachment to the 2nd Battalion of the Grenadiers in November 1915. The following January 1916, Cavan was placed at the head of XIV Corps and took part in the Battle of the Somme that Summer. He was made a Grand Officer of the Belgian Order of the Crown on 2 November 1916 and appointed a Knight of the Order of St Patrick on 18 November 1916. Promoted to lieutenant general on 1 January 1917, he led his Corps at the Battle of Passchendaele in Summer 1917. He was awarded the rank of Grand Officer of the Legion of Honour on 25 September 1917 and was redeployed with his Corps to Italy in October 1917. Advanced to Knight Commander of the Order of the Bath on 1 January 1918, Cavan was appointed Commander-in-Chief of the British Forces in Italy on 10 March 1918. After reverses on the Western Front in March and April 1918, Prime Minister Lloyd George and the War Cabinet had been keen to remove Field Marshal Sir Douglas Haig as Commander-in-Chief of the BEF, but had been unable to think of a suitable successor. In July Cavan was summoned to London, supposedly to discuss the Italian Front but in reality, as Cabinet Secretary Maurice Hankey put it, "to 'vet' him with a view to his replacing Haig" Hankey claimed to have dissuaded the Prime Minister by pointing to Cavan's lack of ideas as to how to defeat the Austro-Hungarians. Haig's victory at Amiens in August secured his position. On the Italian Front Cavan led the Tenth Army