The Second Battle of Artois (French: Deuxime bataille de l'Artois, German: Lorettoschlacht) from 9 May to 18 June 1915, took place on the Western Front during the First World War. A German-held salient from Reims to Amiens had been formed in 1914 which menaced communications between Paris and the unoccupied parts of northern France. A reciprocal French advance eastwards in Artois could cut the rail lines supplying the German armies between Arras and Reims. French operations in Artois, Champagne and Alsace from NovemberDecember 1914, led General Joseph Joffre, Generalissimo (Commander in Chief) and head of Grand Quartier Gnral (GQG), to continue the offensive in Champagne against the German southern rail supply route and to plan an offensive in Artois against the lines from Germany supplying the German armies in the north.

Field Marshal Sir John French, commander of the British Expeditionary Force (BEF), co-operated with the French strategy to capture Vimy Ridge by planning British attacks against Aubers Ridge. The attacks would confront the German 6th Army with a joint offensive, on a 70 mi (110 km) front, eastwards into the Douai plain, where an advance of 1015 mi (1624 km) would cut the railways supplying the German armies as far south as Reims. The French attacked Vimy Ridge and the British attacked further north in the Battle of Aubers Ridge (9 May) and the Battle of Festubert (1525 May).

The battle was fought during the German offensive of the Second Battle of Ypres (21 April 25 May), which the Germans ended to reinforce the Artois front. The initial French attack broke through and captured Vimy Ridge but reserve units were not able to reinforce the troops on the ridge before German counter-attacks forced them back about half-way to their jumping-off points. The British attack at Aubers Ridge was a costly failure and two German divisions in reserve were diverted south against the Tenth Army. The British offensive was suspended until 15 May, when the Battle of Festubert began and French attacks from 15 May to 15 June were concentrated on the flanks to create jumping-off points for a second general offensive, which began on 16 June.

The British attacks at Festubert forced the Germans back 1.9 mi (3 km) and diverted reserves from the French but the Tenth Army gained little more ground, despite firing double the amount of artillery ammunition and many more casualties on both sides. On 18 June, the main offensive was stopped and local French attacks were ended on 25 June. The French had regained 6 sq mi (16 km2) of territory but their failure to capture Vimy Ridge, despite the expenditure of 2,155,862 shells and suffering 102,500 casualties, led to recriminations against Joffre. The defence of the ridge cost the German 6th Army 73,072 casualties. A lull in the area followed until the Third Battle of Artois in September.

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.