The cloud of war rapidly spread over the whole of the South African horizon, and the strategical situation became sharply defined. As regards the determination of the plan of offence referred to in the above War Office despatch, the difficulty was due to the hope entertained by the Cabinet that, in the event of war between this country and the Transvaal, the Orange Free State would remain neutral. The choice in that case would have lain between an advance based on Warrenton, _i.e._, on the Kimberley-to-Mafeking railway, or a movement parallel to the Natal-to-Johannesburg railway. By the middle of 1899, however, the Headquarter staff at the War Office were convinced that, if war should supervene, the two republics would make common cause. A memorandum, entitled, "The Direction of a Line of Advance Against the Transvaal," was prepared by the Intelligence division on that basis and submitted on 3rd June, 1899. It was contended in this memorandum that the lack of any railway between Fourteen Streams and the Transvaal capital eliminated that route from consideration, and that the choice now lay between the line running up through the centre of the Free State and the Natal route. [Sidenote: The better line.] In comparing the relative merits of these two routes it was shown that strategically the Natal line would, owing to the shape of the frontier and the parallel screen of the Drakensberg, be constantly exposed to dangerous flank attacks, while the flanks of the Free State route would be comparatively safe. "The Basutos' sympathies will be entirely with us, while on the west the garrison of Kimberley will hold the approaches." [Sidenote: Reasons.] Tactically, it was pointed out, the Natal route traversed "an ideal terrain for the Boers," and crossed the "immensely strong" position of Laing's Nek. On the other hand, a force advancing by the Free State route, once over the Orange river, would have only to deal with the Bethulie position, and would then reach open plains, which "afford the freest scope for the manoeuvres of all three arms." [Sidenote: Conclusion.] Furthermore, the Free State route could be fed by three distinct lines of railway from three ports, while the Natal route would be dependent on a single line and one port. The memorandum, therefore, submitted the conclusion that "the main line of advance against the Transvaal should be based on the Cape Colony, and should follow generally the line of railway through the Orange Free State to Johannesburg and Pretoria." [Sidenote: Natal threatened.]