Turkish forces are expanding into the Caucasus, taking advantage of the collapse of Russian power there. This worries their German allies. The Germans have their own plans for the Caucasus and favour the establishment of pro-German client states in the region, not its absorption into the Ottoman Empire. They also fear that the Turks are putting too much resources into the Caucasus when the real danger is Allenby‘s British Empire and Commonwealth army in Palestine.
Allenby has launched a series of diversionary operations towards Deraa in Syria, with the assistance of the ever-growing regular forces of the Arab Revolt. Together with guerrilla operations by Arab raiders (assisted by British liaison officer T.E. Lawrence), these have convinced Liman von Sanders, commander of Turkish forces in Palestine, that Allenby is planning an attack in the Transjordan or Syrian regions. He transfers troops from coastal Palestine to reinforce Deraa.
The worst fear of the Germans are confirmed today. Allenby has in conditions of total secrecy concentrated a mighty strike force north of Jaffa. After a devastating artillery bombardment, the infantry attacks, forcing their way through the Turkish defensive lines on the coastal plain. The outnumbered Turks fight as best they can but are soon put to flight. And once the infantry is through the Turkish defensive positions Allenby is able to release his Australian and Indian cavalry to exploit the victory. As the cavalry surge forward towards the town of Megiddo, the cohesion of the Turkish army begins to collapse. Isolated units put up staunch resistance but others take to their heels, surrender, or exchange their uniforms for civilian clothes and abandon the army life.
Positions at start of the battle & at midnight on 19th/20th September (Wikipedia: Battle of Nablus (1918))