German General Friedrich Freiherr Kress von Kressenstein was commander of the three divisions of the Fourth Army. He further strengthened his defensive line stretching from Gaza to Beersheba after the EEF defeats at the first and second battles of Gaza in March and April 1917, and received reinforcements of two divisions. Meanwhile, Lieutenant General Philip Chetwode (commanding the EEF's Eastern Force) began the Stalemate in Southern Palestine, defending essentially the same entrenched lines held at the end of the second battle. He initiated regular mounted reconnaissance into the open eastern flank of the Gaza to Beersheba line towards Beersheba. In June, the Ottoman Fourth Army was reorganized when the new Yildirim Army Group was established, commanded by German General Erich von Falkenhayn. At about the same time, British General Edmund Allenby replaced General Archibald Murray as commander of the EEF. Allenby reorganized the EEF to give him direct command of three corps, in the process deactivating Chetwode's Eastern Force and placing him in command of one of the two infantry corps. At the same time, Chauvel's Desert Column was renamed the Desert Mounted Corps. The stalemate continued through the summer in difficult conditions on the northern edge of the Negev Desert, while EEF reinforcements began to strengthen the divisions which had suffered more than 10,000 casualties during the two battles for Gaza.