Once the crossing over the Jordan at Jisr el Damieh was in our hands, the Turkish IVth Army east of the river would find itself isolated, with its communications cut (at Deraa), and exposed to the converging attacks of our force in the valley, which would hold the river crossings, and of the Arab forces on the east. At the beginning of September a mobile column of the Arab Army, accompanied by armoured cars and a mountain battery, was assembling at Kasr el Azrak, in the desert fifty miles east of Amman, under the energetic direction of Lawrence.
The first essential for the success of the plan was to conceal from the enemy the considerable concentration of troops on the coastal plain, especially that of the three cavalry divisions.
It is doubtful if there has ever been a greater master of the art of deception in war than the British Commander-in-Chief. No detail was too small, no dodge too insignificant to engage his full attention. The two trans-Jordan raids had given the enemy the impression that we intended to attack either up the Jordan Valley, or east of it, at Amman and along the Hedjaz Railway, and General Allenby now set himself to foster this belief by every possible means.
To this end he ordered Major-General Chaytor, who was in the Jordan Valley, in command of a mixed force consisting of the Anzac Mounted Division and eight battalions of infantry, to make a series of demonstrations, with the object of inducing the enemy to believe that an attack east of Jordan was intended. The camps in the valley vacated by the cavalry were left standing, and other camps were pitched there, and occupied by a few men, to show signs of movement, and to make tracks about, and leading to, the camps, in order to deceive enemy airmen. New bridges were thrown across the Jordan, miles of Décauville railway were laid, and thousands of dummy horses were erected on dummy horse lines in the dummy camps. Every day, for some considerable time, a battalion or two of infantry marched down the Jerusalem-Jericho road from Talaat el Dumm, and occupied one or other of these camps. During the night they were brought back to Talaat el Dumm, in returning empty motor lorries, ready to march back again next day. These troops could be plainly seen, marching down into the valley, by the enemy at Shunet Nimrin, who was thus induced to believe that a considerable concentration was taking place in the valley. This unpleasant daily promenade fell to the lot of the British West Indies regiments.
For the benefit of the native population, elaborate bogus preparations were made for the removal of G.H.Q. to Jerusalem. One of the hotels there was cleared of its occupants, much to their disgust, and staff officers busied themselves installing office furniture and telephone equipment, and painting the names of a multitude of departments on the doors of the rooms.
Lastly, lest a chance word should reach a native enemy spy within our lines, everything was done to further the belief among our own troops that we were likely to attack on the east flank. The writer remembers receiving a visit one day from his Divisional General, and being told to do nothing to discourage the idea that the cavalry would once again find themselves in the Valley of Desolation. He also remembers vividly the lurid language that arose on all sides when this report spread about the camps!
No orders were committed to paper other than those issued by G.H.Q. and the three Corps. Secret conferences were called in turn at the various Divisional Headquarters, when the scheme was explained to staffs and commanders of brigades, each of whom then prepared his scheme, and submitted it verbally to his immediate superior.
The three cavalry divisions on the left of our line were hidden securely from the eyes of enemy aeroplane observers; the Australian Mounted Division in the immense, old olive woods round Ramleh, the 4th Cavalry Division in the orange groves near Selmeh, and the 5th Division, which had left the Jordan Valley on September 11, in those north-west of Sarona.
Shortly before the operations commenced, the 60th and 75th Infantry Divisions were brought across to the coastal sector, where they remained, unseen by the enemy, till the attack was launched.
During all the period of concentration, the magnificent work of the Royal Air Force played a dominant part in keeping the enemy in ignorance of our movements. The Commander-in-Chief paid the force a well-deserved compliment in his despatch when he said: 'The chief factor in the secrecy maintained must be attributed, however, to the supremacy in the air which had been obtained by the Royal Air Force. The process of wearing down the enemy's aircraft had been going on all through the summer. During one week in June 100 hostile aeroplanes had crossed our lines. During the last week in August this number had decreased to eighteen. In the next few days a number were shot down, with the result that only four ventured to cross our lines during the period of concentration.'[23]