The campaign in German East Africa had now entered on its most difficult period. Owing to the enormous wastage in men and horses, transport of all kinds was most difficult and in some cases impossible during the rainy season. Writing from Tanga on November 11th, 1916, to Chapman, he says:—
"The war has now entered upon a very difficult phase. As von Lettow-Vorbeck—a very able and determined man—the German commander, has been allowed to escape with considerable forces well equipped with machine-guns, into the wilderness towards the Portuguese border. We hold all the ports, all the towns, plantations, etc., and both the railway lines—but von Lettow still commands a force, it is thought, of over 1000 whites and several thousand trained black troops, well found in arms and ammunition. The wastage from fever and dysentery has been terrible, and, as the heavy rains will come on, where the Germans are, very shortly now, if Smuts cannot round them up quickly it will be impossible to continue this campaign for months. He is busy repairing roads and railways and getting up supplies to near the Front, and we are expecting to get forward again at any moment. With the latest drafts our battalion has had 1400 men out here. All we have left of them are 149 at Kijabe (but these must mostly be unfit for further hard service) and 394 here, of which latter number 101 are sick. Two have died in hospital this week. Of the two fine Rhodesian regiments, it is said that only 68 are fit. The North Lancs Regt. has wasted to nothing, in spite of many drafts. The position is now most difficult, and unless a decision can quickly be arrived at, this campaign may drag on for months and have to be finished by black troops, as another month in a heavy rainy season, without shelter and short rations, will lay out all the white troops still left.
"F. C. S."
"During the period March-September, 1916, General Smuts captured the region from Kilimanjaro to Dar-es-Salaam, whilst the Belgians gradually occupied the western part of German East Africa, from the Great Lakes to Tabora, and General Northey the south-west part of the country. The Germans were thus restricted to the south, the south-centre and south-eastern regions, except the actual coast-line.
"After evacuating Tabora the German troops in that region, who were under General Wahle, retired south-east towards Mahenge, a government station on a high plateau centrally situated between the northern end of Lake Nyasa and the sea at Kilwa. Part of the enemy force which had opposed General Smuts also retreated to Mahenge, its commanding officer being Major Kraut. In its retreat General Wahle's force harried, and was harried by, General Northey's columns. Wahle broke through the British lines and joined Kraut, who was being threatened from the north by General Van Deventer, the commander of General Smuts' Second Division. In the closing days of 1916 and the beginning of 1917 a combined effort was made by Generals Van Deventer and Northey to 'round up' the Germans holding the Mahenge plateau. The movement promised success, but, in the words of General Smuts, the enemy 'eventually escaped through the dense bush and forest under cover of darkness, and eluded pursuit.'
"Meantime the main enemy force, under Colonel von Lettow-Vorbeck, upon whom the Kaiser in November, 1916, conferred the Ordre Pour le Merite, had been driven by General Smuts to the region of the Rufigi, south of Dar-es-Salaam. At this period General Smuts reorganized his forces, and, in view of the extremely unhealthy character of the country in which further operations were to be conducted, as many as possible of the white troops from South Africa were sent home, over 12,000 leaving East Africa between the middle of October and the end of December, 1916. They were replaced by newly raised battalions of King's African Rifles and by a Nigerian Brigade under General Cunliffe. On January 1, 1917, General Smuts began a new offensive in the Rufigi area, his object being to cut all connection between the enemy in the Rufigi and Mahenge regions and either to envelop the enemy on the Rufigi or to deal a heavy blow as he escaped south. The last object was accomplished; a heavy blow was inflicted upon von Lettow-Vorbeck's force, but it was not brought to a decisive engagement. This brief campaign was ended in March by the advent of the rainy season. While it was in progress General Smuts was summoned to England to represent South Africa in the special sittings of the War Cabinet. He relinquished his command on January 20, 1917, being succeeded by Major-General A. R. Hoskins, C.M.G., D.S.O., who had previously commanded the First Division."— "The Times History and Encyclopædia of the War," the campaign in German East Africa (III), pp. 397-398.
On December 8th, the Royal Fusiliers went in open trucks by rail to Mikesse, near Morogoro, and from thence had a very trying eight days' march to Kissaki. During this and previous marches Selous never rode a yard of the way, but marched like his men, living on their rough fare and enduring the constant rain and soaking bivouacs with stoical indifference. On December 15th he writes to his wife from Tulo:—
"We are now marching to Kissaki, and from there will probably advance and attack the Germans on the Rufigi river. Very heavy rains have now set in, and we have had rather a bad time of it, and our detachment has shrunk from 384 to 170, with which we march to-day. We hear the bridge over the Rufigi river has been washed away by the floods and the German forces cut in two."
One of his last letters, written on Christmas Day, 1916, from Kissaki, states:—
"We are on the eve of an attack on the Germans out here. Their lines here are quite close to ours, our forces are gathering, and we shall now attack their lines in several places simultaneously in a few days. Our forces are terribly depleted principally from sickness. The German forces are sure to be entrenching, and as they still have a number of machine-guns, it may be no child's play attacking their positions, and we may meet with heavy losses."