The Third Battle of Gaza was fought on the night of 12 November 1917 between British and Ottoman forces during the Sinai and Palestine Campaign of World War I and came after the British Egyptian Expeditionary Force (EEF) victory at the Battle of Beersheba had ended the Stalemate in Southern Palestine. The fighting occurred at the beginning of the Southern Palestine Offensive, and, together with attacks on Hareira and Sheria on 67 November and the continuing Battle of Tel el Khuweilfe, which had been launched by General Edmund Allenby on 1 November, it eventually broke the Gaza-to-Beersheba line defended by the Yildirim Army Group. Despite having held this line since March 1917, the Ottoman Army was forced to evacuate Gaza and Tel el Khuweilfe during the night of 67 November. Only Sheria held out for most of the 7 November before it too was captured.Following British defeats at the First and Second battles of Gaza in March and April 1917, Lieutenant General Philip Chetwode commanding the EEF's Eastern Force and Kress von Kressenstein's Ottoman Empire force had each adopted a defensive posture and a stalemate had developed in Southern Palestine. Entrenched defences approximately on the lines held at the end of the second battle were strengthened, and both sides undertook regular mounted reconnaissances into the open eastern flank. In late June, Allenby replaced General Archibald Murray as commander of the EEF, which he quickly reorganised. At about the same time, the Ottoman Fourth Army was also restructured. As the stalemate continued in terrible conditions through the summer, reinforcements began to arrive to replace the large number of casualties suffered by the EEF during the previous fighting for Gaza, while several additional divisions also arrived. The Ottoman defenders were also reinforced at this time, and both sides carried out training while manning the front lines and monitoring the open eastern flank. By mid-October, as the Battle of Passchendaele continued on the Western Front, the last of the British reinforcements arrived as Allenby's preparations to commence a campaign of manoeuvre neared completion.

Prior to the Second Battle of Gaza, the town had been developed into a strong modern fortress, with entrenchments, wire entanglements and a glacis on its south and southeastern edges. A series of field works, mutually supported by artillery, machine guns and rifles, extended from Gaza eastwards to within 4 miles (6.4 km) of Beersheba. Beginning on 27 October, the EEF began a heavy and almost continuous bombardment of Gaza. During this time, the EEF's XXI Corps, holding the Gaza section of the line, had been mostly passive until the night of 1/2 November, when a series of determined night-time assaults were mounted against the Gaza defences. Yet these attacks were only partially successful due to the strength of the garrison. The bombardment of Gaza intensified on 6 November and during the night of 6/7 November successful attacks were launched on several trench systems. On the morning of 7 November, Gaza was found to have been evacuated during the night. The Gaza to Beersheba line subsequently collapsed and the Ottoman Seventh and Eighth Armies were forced into retreat. Following several battles during the pursuit, the EEF captured Jerusalem on 9 December 1917.

World War I, often abbreviated as WWI or WW1, also known as the First World War and contemporaneously known as the Great War and by other names, was an international conflict that began on 28 July 1914 and ended on 11 November 1918. It involved much of Europe, as well as Russia, the United States and Turkey, and was also fought in the Middle East, Africa and parts of Asia. One of the deadliest conflicts in history, an estimated 9 million were killed in combat, while over 5 million civilians died from occupation, bombardment, hunger or disease. The genocides perpetrated by the Ottomans and the 1918 Spanish flu pandemic spread by the movement of combatants during the war caused many millions of additional deaths worldwide.In 1914, the Great Powers were divided into two opposing alliances: the Triple Entente, consisting of France, Russia, and Britain, and the Triple Alliance, made up of Germany, Austria-Hungary, and Italy. Tensions in the Balkans came to a head on 28 June 1914 following the assassination of Archduke Franz Ferdinand, the Austro-Hungarian heir, by Gavrilo Princip, a Bosnian Serb. Austria-Hungary blamed Serbia and the interlocking alliances involved the Powers in a series of diplomatic exchanges known as the July Crisis. On 28 July, Austria-Hungary declared war on Serbia; Russia came to Serbia's defence and by 4 August, the conflict had expanded to include Germany, France and Britain, along with their respective colonial empires. In November, the Ottoman Empire, Germany and Austria formed the Central Powers, while in April 1915, Italy joined Britain, France, Russia and Serbia as the Allied Powers.

Facing a war on two fronts, German strategy in 1914 was to defeat France, then shift its forces to the East and knock out Russia, commonly known as the Schlieffen Plan. This failed when their advance into France was halted at the Marne; by the end of 1914, the two sides faced each other along the Western Front, a continuous series of trench lines stretching from the Channel to Switzerland that changed little until 1917. By contrast, the Eastern Front was far more fluid, with Austria-Hungary and Russia gaining, then losing large swathes of territory. Other significant theatres included the Middle East, the Alpine Front and the Balkans, bringing Bulgaria, Romania and Greece into the war.

Shortages caused by the Allied naval blockade led Germany to initiate unrestricted submarine warfare in early 1917, bringing the previously neutral United States into the war on 6 April 1917. In Russia, the Bolsheviks seized power in the 1917 October Revolution and made peace in the March 1918 Treaty of Brest-Litovsk, freeing up large numbers of German troops. By transferring these to the Western Front, the German General Staff hoped to win a decisive victory before American reinforcements could impact the war, and launched the March 1918 German spring offensive. Despite initial success, it was soon halted by heavy casualties and ferocious defence; in August, the Allies launched the Hundred Days Offensive and although the German army continued to fight hard, it could no longer halt their advance.Towards the end of 1918, the Central Powers began to collapse; Bulgaria signed an Armistice on 29 September, followed by the Ottomans on 31 October, then Austria-Hungary on 3 November. Isolated, facing revolution at home and an army on the verge of mutiny, Kaiser Wilhelm abdicated on 9 November and the new German government signed the Armistice of 11 November 1918, bringing the fighting to a close. The 1919 Paris Peace Conference imposed various settlements on the defeated powers, the best known being the Treaty of Versailles. The dissolution of the Russian, German, Ottoman and Austro-Hungarian empires led to numerous uprisings and the creation of independent states, including Poland, Czechoslovakia and Yugoslavia. For reasons that are still debated, failure to manage the instability that resulted from this upheaval during the interwar period ended with the outbreak of World War II in 1939.