Falkenhayn, now in command at Aleppo, had also been plan ning an offensive, but the better communications of the British had decided the race, and although Falkenhayn tried to stem the tide by a counter-stroke against Beersheba, the breaking of his centre compelled a general retreat. The pursuit was hampered owing to lack of water, but, even so, by Nov. 14 the Turkish forces were driven apart in two divergent groups, the port of Jaffa was taken, and Allenby wheeled his main force to the right for an advance inland on Jerusalem. He gained the narrow hill passes before the Turks could block them, and after a necessary pause to improve his communications, brought up reserves for a fresh advance, which secured Jerusalem on Dec. 9. By the time the winter rains set in the British had expanded and consolidated their hold on the region. As a moral success the feat was valu able, yet viewed strategically, it seemed a long way round to the goal. If Turkey be pictured as a bent old man, the British, after missing their blow at his head—Constantinople—and omitting to strike at his heart—Alexandretta—had now resigned themselves to swallowing him from the feet upwards, like a python dragging its endless length across the desert.
The year 1917 witnessed another overseas success, the clearing of German East Africa, although not the close of the campaign. More than a year elapsed after the rebuff at Tanga before a serious attempt was made to subdue the last German stronghold on the African continent. To spare troops from the main theatres was difficult, and the solution was only made possible by the loyal co-operation of the South African Government. In Feb. 1916 Gen. Smuts was appointed to command the expedition, and formed the plan of a drive from north to south through the difficult interior, in order to avoid the fever-rampant plain on the coast. In conjunction with this central wedge, a Belgian force under Tombeur was to advance eastwards from Lake Tanganyika, and a small British force under Northey was to strike in from Nyasaland in the south-west. The Germans under Lettow-Vorbeck were weak in numbers but handled with masterly skill, and with all the ad vantages of an equatorial climate, a vast and trackless region— mountainous in parts and covered with dense bush and forest— to assist them in impeding the invader. From Dar-es Salaam on the coast to Ujiji on Lake Tanganyika ran the one real line of rail communication, across the centre of the colony. After driving the Germans back across the frontier and seizing the Kiliman jaro gap, Smuts moved direct on this railway at Morogoro, over 30o m. distant, while he dispatched a force under Van Deventer in a wide sweep to the west to cut the railway further inland and then converge on Morogoro. Lettow-Vorbeck de
layed this manoeuvre by a concentration against Van Deventer, but Smuts's direct advance compelled him to hurry his force back, and thus enabled Van Deventer to get astride the railway.
However, Letto-Vorbeck evaded the attempt to cut him off and fell back in September on the Uluguru mountains to the south. The Belgians and Northey had cleared the west, and the net had been drawn steadily closer, confining Lettow-Vorbeck to the south-east quarter of the colony. Early in 1917 Smuts returned to England, and Van Deventer conducted the final operations which ended with Lettow-Vorbeck, avoiding envelopment to the end, slipping across the frontier into Portuguese Africa. Here he maintained a guerrilla campaign throughout 1918 until the general Armistice. With an original force of only 5,000, 5% being Europeans, he had caused the employment of 130,000 enemy troops and the expenditure of L72,000,000.
The military side of 1917 is thrown into shadow by the naval, or more strictly the economic, side. The vital issue turned on the balance between Germany's submarine pressure and Britain's resistance. April was perhaps the most critical month. The Allies lost nearly a million tons of shipping, 6o% British, and although the German navy's promise of victory by the end of the month was proved a miscalculation, it was clear that, ultimately, the continuance of such a ratio of loss must starve the civilian population and automatically prevent the maintenance of the armies. Britain, indeed, had only food enough to sustain her people for another six weeks. The British Government sought to counter the menace by the indirect means of rationing, increasing home production and the expansion of shipbuilding; by the direct means of the system of convoys with naval escorts, and a counter-offensive against the submarine. Aided by new devices to detect the pres ence of submarines and the use of thousands of patrol craft, this highly organized campaign exacted an ever-rising toll, and by the end of 1917 the menace, if not broken, was at least sub dued. In this task America's aid became a potent factor long before her military assistance. It embraced her provision of light craft to reinforce the British anti-submarine fleet, her rapidly developed construction of new mercantile ships, and still more her financial aid. By July 1917 Britain had spent over is,000, 000,000, her daily expenditure had risen to £7,000,000, and the burden of financing her Allies as well as her own efforts was straining even her resources, when America's aid came to ease the pressure.