Allenby needed to establish a defensive line running from the Mediterranean Sea which could be held with reasonable security once his right flank was secured on the Dead Sea.
In order to consolidate a strong British Empire line, it was necessary to push the 3rd and 7th Infantry Divisions of the Ottoman Eighth Army back away from the Nahr el Auja 4 miles (6.4 km) north of Jaffa on the Mediterranean coast.
The first attempt was made on 24 to 25 November and this second engagement in the same area became officially designated by the British as a subsidiary battle during the Jerusalem Operations.

Three infantry divisions of the XXI Corps began moving their units into position on the coastal plain on 7 December.
The 75th Division was on the right with the 54th (East Anglian) Division in the centre and the 52nd (Lowland) Division on the coast.
Infantry from the 162nd (East Midland) Brigade, relieved the New Zealand Mounted Rifles Brigade in the front line on 11 December and the mounted riflemen, who had been heavily involved in the earlier attempt to capture the Nahr el Auja, moved back to bivouac near Ayun Kara.

Military operations resumed a fortnight after the surrender of Jerusalem with the final attack of this campaign.
But preparations were complicated by the sodden state of the low and swampy ground on the southern banks of the Nahr el Auja where the attack would be launched.
And the river was swollen by rain which had fallen on 19 and 20 December.
From Mulebbis to the sea the river is between 40–50 feet (12–15 m) wide and 10–12 feet (3.0–3.7 m) deep except for the ford at the mouth of the river known as Sheik Muanis.
To the north of the river two prominent spurs run down to the river from a series of sandy ridges.
These overlooked the damaged stone bridge at Khurbet Hadrah to the east and the village of Sheik Muannis, near Jerisheh to the west where a mill dam bridged the stream.
The Ottoman Eighth Army held strong commanding positions covering all the places used by the attackers in November.
They held both spurs in addition to a post opposite the ford at the mouth of the Nahr el Auja.
They also held a line extending east of Khurbet Hadrah which crossed to the south bank of the river to include Bald Hill and Mulebbis.

All three infantry brigades of the 52nd (Lowland) Division managed to cross the River Auja on the night of 20–21 December.
It is claimed that by morning they had secured the Ottoman defensive line, completely surprising the defenders who surrendered without firing a shot.
Temporary bridges were built so the infantry's artillery could cross the river.
On 23 December the 52nd (Lowland) and 54th (East Anglian) Divisions moved up the coast a further 5 miles (8.0 km), while the left of the advance reached Arsuf 8 miles (13 km) north of Jaffa, capturing key Ottoman defensive positions.
They were supported by guns on British warships.
Three hundred prisoners were captured and many Ottomans were killed with bayonets, while the British infantry suffered 100 casualties.
Allenby needed to establish a defensive line running from the Mediterranean Sea which could be held with reasonable security once his right flank was secured on the Dead Sea. In order to consolidate a strong British Empire line, it was necessary to push the 3rd and 7th Infantry Divisions of the Ottoman Eighth Army back away from the Nahr el Auja 4 miles (6.4 km) north of Jaffa on the Mediterranean coast. The first attempt was made on 24 to 25 November and this second engagement in the same area became officially designated by the British as a subsidiary battle during the Jerusalem Operations.
Three infantry divisions of the XXI Corps began moving their units into position on the coastal plain on 7 December. The 75th Division was on the right with the 54th (East Anglian) Division in the centre and the 52nd (Lowland) Division on the coast. Infantry from the 162nd (East Midland) Brigade, relieved the New Zealand Mounted Rifles Brigade in the front line on 11 December and the mounted riflemen, who had been heavily involved in the earlier attempt to capture the Nahr el Auja, moved back to bivouac near Ayun Kara.
Military operations resumed a fortnight after the surrender of Jerusalem with the final attack of this campaign. But preparations were complicated by the sodden state of the low and swampy ground on the southern banks of the Nahr el Auja where the attack would be launched. And the river was swollen by rain which had fallen on 19 and 20 December. From Mulebbis to the sea the river is between 40–50 feet (12–15 m) wide and 10–12 feet (3.0–3.7 m) deep except for the ford at the mouth of the river known as Sheik Muanis. To the north of the river two prominent spurs run down to the river from a series of sandy ridges. These overlooked the damaged stone bridge at Khurbet Hadrah to the east and the village of Sheik Muannis, near Jerisheh to the west where a mill dam bridged the stream. The Ottoman Eighth Army held strong commanding positions covering all the places used by the attackers in November. They held both spurs in addition to a post opposite the ford at the mouth of the Nahr el Auja. They also held a line extending east of Khurbet Hadrah which crossed to the south bank of the river to include Bald Hill and Mulebbis.
All three infantry brigades of the 52nd (Lowland) Division managed to cross the River Auja on the night of 20–21 December. It is claimed that by morning they had secured the Ottoman defensive line, completely surprising the defenders who surrendered without firing a shot. Temporary bridges were built so the infantry's artillery could cross the river. On 23 December the 52nd (Lowland) and 54th (East Anglian) Divisions moved up the coast a further 5 miles (8.0 km), while the left of the advance reached Arsuf 8 miles (13 km) north of Jaffa, capturing key Ottoman defensive positions. They were supported by guns on British warships. Three hundred prisoners were captured and many Ottomans were killed with bayonets, while the British infantry suffered 100 casualties.
Battle of Jerusalem