Answer
Sir John French relieved Smith-Dorrien of his command of the Second Army on 10 December 1914. French had been unhappy with Smith-Dorrien's performance during the First Battle of Ypres and had been looking for an excuse to replace him. He found the excuse when Smith-Dorrien ordered a retreat from the village of Messines on 9 December, which French considered to be unnecessary. French replaced Smith-Dorrien with General Sir Horace Smith-Barry.