British army contingents sent to France at the outbreak of World War I. Following the army reforms of Richard Haldane a territorial reserve army had been created. This was immediately mobilized when war was declared on 4 August 1914 and, together with regular troops, sent to France under Sir John French. An expeditionary force was again mobilized and sent to France in September 1939 but, after failing to halt the German advance across the Low Countries and France, had to be rescued in the Dunkirk evacuation.