France in the month war was declared as part of the 10th Brigade in the 4th Division. The Division was part of the British Expeditionary Force (BEF), the professionals of the old regular army, known as the 'Old Contemptibles' after a comment made by the German Kaiser. The 2nd Dublins took part in the retreat following the Battle of Mons, taking part in their first engagement on 26 August 1914 at Le Cateau that helped delay the German advance towards Paris, inflicting such heavy casualties that the Germans thought they faced more machine-guns than they actually did. The BEF then resumed their retreat, but many men, including from the Dublin Fusiliers, were stranded behind German lines, and many were taken prisoner by the Germans. The Battalion, badly depleted, later took part in the Battle of the Marne (5–9 September) that finally halted the German advance just on the outskirts of Paris, forcing the Germans to retreat to the Aisne. There, the 2nd Dublins took part in the Battle of the Aisne and later took part in their last major engagement of the war, at the Battle of Messines, which began on 12 October and ended on 2 November. The 2nd Dublins took part in all but one of the subsidiary battles during Second Ypres that took place between 22 April – 24 May 1915. The Battalion suffered heavily at the Battle of St Julien, the second subsidiary battle, incurring hundreds of casualties. They had no respite, taking part in the next two subsidiary battles at Frezenberg and Bellewaarde. On 24 May the Battalion was subject to a German poison gas attack near Saint-Julien and effectively disintegrated as a fighting unit. The British at that time had no defences against gas attack; indeed the large-scale use of gas by the Germans on the Western Front had begun at Second Ypres. The 2nd Dublins' commanding officer, Lieutenant Colonel Arthur Loveband of Naas, died the following day. The Battalion did not take part in any more major battles for the rest of the year. The 8th and 9th Dublins, who had arrived in France in December 1915 as part of the 48th Brigade in the 16th (Irish) Division, were also subject to a German gas attack at the Battle of Hulluch, near Loos, on 27 April 1916, suffering heavy casualties. There had been trouble at home that month in Dublin when the Easter