s, and detachments watched the intermediate crossings.
The attacks of the Ladysmith garrison on Gun Hill and Surprise Hill
and the destruction of the Waschbank bridge produced a considerable
feeling of uneasiness at Boer Headquarters soon after Sir Redvers
reached Frere. Their own official records show that there was a
reluctance to detach any more burghers than were deemed absolutely
necessary to the Tugela. Having regard to these facts, although no
exact figures can be given, it is probable that an estimate made on
13th December by General Buller's Intelligence staff, that about
6,000 to 7,000 men had been concentrated under Louis Botha in the
neighbourhood of Colenso, was not far from the mark. On the other
hand, the Boer official telegrams of that date put the number as low
as 5,000.

[Footnote 215: Map No. 3.]

[Sidenote: Close connection between Boer main army in Natal and
Botha.]

Botha's detachment and the Boer main army were, however, within an
hour's ride of each other, and thus could readily render mutual
assistance, unless an attack from the south should be combined with an
exactly-timed sortie by the Ladysmith garrison. Yet the Boers had
reason to fear this combination against them. The troops under Sir
George White were still mobile, and the enterprises against Gun Hill
and Surprise Hill, in the second week of December, had shown that both
officers and men were keen to be again let slip at the enemy.[216]
Moreover, the large number of mounted men, who, though shut up in
Ladysmith, were in fact astride of the Boers' lines of communication,
both with the Transvaal and with the Free State, would be likely to
prove a serious danger in the event of Botha's defeat by Sir Redvers.

[Footnote 216: See Volume II.]

[Sidenote: A formidable natural fortress.]

Nevertheless, the task which the British commander-in-chief had decided
to undertake was not an easy one. From Potgieters Drift on the west to
the junction of the Tugela with Sunday's river, about 30 miles east of
Colenso, a ridge of hills, broken only by narrow kloofs and dongas, line
like a continuous parapet the northern bank of the former river.
Westward the ridge is connected by the Brakfontein Nek with that spur of
the Drakensberg which is entitled the Tabanyama Range. This was
destined, a month later, to bar the advance of the relieving army on
that side. The eastern flank was guarded by the lower slopes of the
Biggarsberg, whic