Field Marshal Lord Roberts replaced Buller as British Commander-in-Chief in South Africa in January 1900. Within a month Roberts assembled 30,000 infantry, 7,501 cavalry and 3,600 mounted infantry, together with 120 guns, in the area between the Orange and Modder Rivers. The largest British mounted division ever assembled was created under the command of Major-General John French through the amalgamation of virtually all the cavalry in the area. News of the shelling by the Boer Long Tom gun had reached Lord Roberts, whose parting words to his officers on 9 February were that "You must relieve Kimberley if it costs you half your forces."