Fighting along with the rest of the BEF against overwhelming odds in August 1914, Smith-Dorrien managed his command ably in defensive battles at Mons and Le Cateau. In the latter engagement, Smith-Dorrien was forced into the unenviable decision to fight with exhausted troops and open flanks against a numerically superior enemy force. To retreat, though not contrary to orders, would probably have turned the British withdrawal into a rout, possibly resulting in the destruction of the BEF. Heavy fighting in unprepared positions against three German divisions of Von Kluck's corps resulted in over 8,000 British casualties but delayed the enemy advance long enough to permit resumption of the withdrawal.
After participating in First Ypres in October 1914, the II Corps was taken out of the line, and, in the reorganization of the BEF that followed, Smith-Dorrien was appointed to command the Second Army. He again led his troops well during the German attack at Second Ypres in April 1915. Repeatedly ordered into costly and seemingly senseless counter-attacks, Smith-Dorrien halted the attacks on his own initiative and recommended the partial abandonment of badly exposed sectors of the Ypres salient. Sir John French, however, perhaps motivated by political considerations (Ypres had come to mean much the same to the British as would Verdun to the French a year later), and bearing little affection for his subordinate, relieved Smith-Dorrien. His capable replacement, General Sir Herbert Plumer, assessed the situation in much the same manner as had his predecessor; French was thus forced ultimately to accept most of what Smith-Dorrien had originally proposed. Smith-Dorrien himself, however, was never again to command in the field.
Sources: Smithers, A.J. Smithers, The Man Who Disobeyed: Sir Horace Smith-Dorrien and His Enemies. London: Leo Cooper, 1970.
Pope, Stephen and Elizabeth Anne-Wheal, The Dictionary of the First World War. New York: St. Martin's Press, 1995.
Wilson, Trevor, The Myriad Faces of War. Cambridge: Polity Press, 1986.