The South African War at one time threatened to produce a siege, that of Pretoria, where fairly modern forts with modern armaments were known to exist. At the same time the enemy at Modder River were giving us some trouble with their heavy artillery. The Navy came to our rescue with heavy B.L. guns mounted on wheels. With a view to trying the use of the railway itself, it was pointed out that the railway department had both the shops and the goodwill to mount heavy guns, if required. This offer was approved, and in a few weeks the two heaviest siege guns ever seen in the field were made ready. The carriages, designed by the combined wit of the machinery officers and the Chief Locomotive Superintendent of the Cape Government Railway, were most creditable achievements, old engine and tender frames being used as a foundation. The guns mounted were a 6-inch B.L., and no less a monster than a 9·2 inch B.L. The 6-inch went into action at Modder River. It was deemed unsafe to fix it at an angle of more than sixteen degrees to either side of the centre line of the railway; but by placing it on a so-called firing curve a wider field of fire was secured. The gun behaved exceedingly well in every way; and later on it was fired at right angles to the railway, without any damage either to itself or to the line. The 9·2-inch gun gave good results in its trials, but, although it was run up to Pretoria on its truck, there was no opportunity of firing it on the enemy. Sir Percy says in his "History" that-- The experiments demonstrated the possibility of big guns being used in siege operations without any difficulty, the only limit to the size of the gun being the weight which the railway bridges will stand. Apart from the powers of usefulness offered by these batteries on wheels, there arose, in the early days of the war, the further question whether the usefulness of armoured trains proper might not be marred as the result of a defective system of control.