As dawn broke, the British discovered that they held only the smaller and lower part of the hilltop of Spion Kop, while the Boers occupied higher ground on three sides of the British position. The British had no direct knowledge of the topography of the summit and the darkness and fog had compounded the problem. Furthermore, the British trenches were inadequate for all defensive purposes. Because the summit of the kop was mostly hard rock, the trenches were at most deep and provided an exceptionally poor defensive position – the British infantry in the trenches could not see over the crest of the plateau and the Boers were able to fire down the length of the crescent-shaped trench from the adjacent peaks.