While the initial attacks by the
XXI Corps, the breakthrough by the
Desert Mounted Corps, and the subsequent XX Corps attack were under way, it was necessary to deploy a force strong enough to defend their right flank in the Jordan Valley against any attack by the
Fourth Army, which covered the EEF occupied Jordan Valley area with long range guns located in the eastern foothills.
Ottoman Fourth Army The Fourth Army consisting of 6,000 infantry and 2,000 cavalry supported by seventy-four artillery pieces was commanded by General
Mohammed Jemal Pasha. The army headquarters was at
Amman, and held the line across the Jordan Valley and southwards along the Hejaz railway. The Fourth Army was composed of the
VIII Corps' 48th Infantry Division, the Composite Division of a German battalion group, the Caucasus Cavalry Brigade, the division sized Serstal Group, the 24th and 62nd Infantry Divisions and a mule-mounted infantry regiment. The 3rd Cavalry Division, German 146th Regiment 63rd Regiment made up the Army Troops. There were 6,000 Ottoman soldiers with 30 guns in the
II Corps, known as the Seria Group or Jordan Group, which garrisoned the Hejaz railway line from Ma'an southwards towards Mecca.
Chaytor's Force This composite force commanded by
Major General Edward Chaytor was "nearly equivalent to two divisions," being a reinforced mounted infantry division of 11,000 men.
Chaytor's Force consisted of the
ANZAC Mounted Division's ::
1st Light Horse Brigade commanded by Brigadier General C. F. Cox ::
2nd Light Horse Brigade commanded by Brigadier General G. de L. Ryrie ::
New Zealand Mounted Rifles Brigade commanded by Brigadier General W. Meldrum the
20th Indian Brigade commanded by Brigadier General E. R. B. Murray ::
110th Mahratta Light Infantry ::Alwar Imperial Service Infantry ::Patiala Imperial Service Infantry ::Gwalior Imperial Service Infantry the 1st and 2nd Battalions
British West Indies Regiment, the 38th and 39th Battalions
Royal Fusiliers, the 86th/26th
Machine Gun Squadron and artillery. The ration strength of Chaytor's Force at the end of operations on 30 September was "8,000 British, 3,000 Indian, 500
Egyptian Camel Transport Corps troops."
Lieutenant General Harry Chauvel, the Australian commander of the Desert Mounted Corps, instructed Chaytor to hold his ground "for the present", but to closely watch the Ottoman forces during around-the-clock patrolling, and to immediately occupy any abandoned enemy positions. As soon as possible Chaytor's Force was to advance northwards to capture and cut a main line of withdrawal for the Ottoman Seventh and Eighth Armies across the Damieh bridge, also a main line of communication between these two armies west of the River Jordan in the Judean Hills with the Fourth Army in the east. By 21 September, only the Fourth Army remained in position and intact after the successful attacks during the Battle of Sharon by the XXI Corps, the Desert Mounted Corps and the beginning of the Battle of Nablus by XX Corps. The destruction of the Fourth Army, which had begun to withdraw to conform with the two other Ottoman armies in the Judean Hills, became Allenby's next priority. Chaytor's Force was to advance eastwards to capture Es Salt and Amman, and to intercept and capture the 4,600-strong southern Hejaz garrison.
Advance northwards After the British West Indies Regiment advances towards Bakr Ridge were consolidated and continued at dawn on 20 September, their 2nd Battalion captured Bakr Ridge along with Baghalat and Chalk Ridge. Although the 38th Battalion Royal Fusiliers was opposed at Mellaha the 2nd Light Horse Brigade and Patiala Infantry, advanced eastwards across the Jordan Valley toward the strongly entrenched Shunet Nimrin position, and Derbasi on the Ottoman left flank although positions east of the Jordan River continued to be strongly held. The Seventh and Fourth Armies had begun to withdraw, and before dawn on 21 September Chaytor ordered the Auckland Mounted Rifles Regiment to advance and capture Kh Fasail, north of Baghalat and about halfway to Damieh, which they had captured by 23:30. The Nablus to Damieh road was captured early in the morning of 22 September by Meldrum's Force which included the New Zealand Mounted Rifles Brigade and the British West Indies Regiment. Subsequently, an attack on the Ottoman garrison holding the bridge at Damieh by the Auckland and Canterbury Mounted Rifles Regiments supported by a battalion of the British West Indies Regiment forced the defenders to retreat in disorder, when the bridge was captured intact. The 2nd Battalion British West Indies Regiment, reinforced by the 3rd Light Horse Regiment (1st Light Horse Brigade), captured the Ottoman rearguard covering the Mafid Jozele ford, despite having encountered a number of Ottoman soldiers withdrawing across the ford. Mafid Jozele was captured by 05:50 on 23 September, but the bridge had been destroyed at the ford. The EEF became aware of the withdrawal of the Fourth Army at 23:35 on 22/23 September, when orders were issued for an attack on Shunet Nimrin, Kabr Mujahid and Tel er Ramr. This was to be carried out by the 2nd Light Horse Brigade and mobile sections of the 20th Indian Brigade, a group that consisted of 1,500 rifles, three sections of machine guns and forty
Lewis guns. This force was to move eastwards along the main Ghoranyeh to Es Salt road towards Shunet Nimrin, while the immobile section was to remain in defence in the right sector of the Jordan Valley occupied zone. The CRA was to support this advance by targeting Shunet Nimrin.
Advance eastwards to Es Salt and Amman Before
Haifa was captured by the
14th Cavalry Brigade (
5th Cavalry Division) on 23 September, Chaytor's Force had crossed the Jordan River to climb to the Plateau of Moab and Gilead on their way to capture Es Salt. An extensive rearguard position, defended by nine officers and 150 other ranks with rifles and machine guns, across the road from Damieh to Es Salt had been attacked and outflanked by the Canterbury Mounted Rifles Regiment advance guard. All defenders were captured, and at 16:20 on 23 September, Es Salt was occupied by the New Zealand Mounted Rifles Brigade. The 2nd Light Horse Brigade was delayed by the difficult track up the Wadis Jeri'a and Sir which did not reach Ain Hummar on the main road east of Es Salt until the afternoon of 24 September. The main road had been blown up in places by the retreating Ottoman Army, forcing Chaytor to pause on 24 September to wait for supplies as well. During the day the New Zealand Mounted Rifles Brigade occupied Suweile and one hundred men from the Auckland Mounted Rifles Regiment took 11 hours to ride , cut the railway north of Amman and return to Suweile. Accompanied by four officers, the raiding group carrying nothing but tools and weapons, advanced to the railway, where they took out a section of the Hedjaz line north of Amman near Kalaat ez Zerka station. Orders were then issued for the New Zealand Mounted Rifles and the 2nd Light Horse Brigades to advance to Amman beginning at 06:00 on 25 September. The 1st Light Horse Brigade was to follow at 06:30, while the 1st Battalion British West Indies Regiment would march to Suweileh to replace the New Zealand Mounted Rifles Brigade garrison by 07:00. If the attackers found Amman was lightly held, they were to strongly assault the place, but if Amman was held in strength the assault on the city was to be deferred until the infantry arrived; only the outlying or forward trenches were to be attacked while artillery was to bombard the place, and all lines of retreat northwards were to be cut. Aerial bombing of Amman was requested. == Battle ==