All along the mountains which mark the western edge of the high plateau one will notice a chain of lakes, from Nyasa in the south through Tanganyika and Kivu to Lake Albert in the north. In prehistoric time some convulsion of nature broke the African continent all along its spine, and formed this system of lakes. Another break occurs on the high plateau, from Portuguese East Africa in the south to British East Africa in the north, along the Great Rift Valley, with its magnificent escarpments and weird scenery, prolonged through Lake Rudolf to the Red Sea and on to the Dead Sea and Jordan Valley. Great volcanoes, now mostly extinct, though some to the north of Kivu are still active, are a still later feature of the country. [Sidenote: Lakes and mountains a frontier for defense.] I have referred to these lakes and to the great mountain-chain along the lakes because they formed the western boundary of German East Africa, and from the point of view of defense made a magnificent frontier so strong that the Belgian forces moving from the Congo found it impossible to invade the enemy territory from the west, and had to be moved in large part northeast before they could strike south. Once there, with their usual dash they did their work remarkably well. [Sidenote: Seaplanes attack German vessels in the lakes.] As soon as this northern column had reached Kigali, the capital of the lofty Ruanda Province, the German forces fell back from the neighborhood of Lake Kivu, and the remainder of the Belgian army was able to advance from the west across the mountain barrier. Simultaneously, and in cooerdination with their advance, strong British columns were moving southward to the west of Victoria Nyanza. As soon as we had reached the southern shores of the lake, a new concerted forward movement by the British and Belgian columns was begun both from Victoria Nyanza and from Tanganyika, where in the meantime the German armed vessels on the lake had been bombed and destroyed by seaplanes, and Ujiji on the eastern shore had been occupied. This movement did not stop until Tabora, with the central railway, was occupied early in September, 1916. [Sidenote: General Northey's advance across the mountain.] At the same time a great movement was made in the south by General Northey, who advanced from the line between Lakes Tanganyika and Nyasa across the mountains flanking the great plateau on the west. This is a very mountainous region; but he got over the mountains, and moving north, took Bismarckburg, Neu Langenburg, and afterward Iringa, where our main forces joined hands with his. These advances, all carried out with great skill and energy against very great physical difficulties, were subsidiary to the principal attack, which was being executed from the north-east, in the neighborhood of Kilimanjaro. [Sidenote: The River Rovuma a strategic line.] [Sidenote: Pursuit of enemy across Rovuma is difficult.]