At the start of the war, the largest of the European belligerents were all colonial powers – they had people and valuable assets stationed in countries all over the Earth. These multinational interests, along with overseas alliances and the modernization of sea transport, are what put the “world” in World War I.

Enemy nations attacked each other’s colonies and fleets, and laborers and soldiers were recruited from colonized countries, and brought to the front lines. Allied countries – many former colonies – shipped soldiers and supplies into battle, coordinating with their European counterparts. And, despite the fact that the Western Front is the best-known theatre of World War I, the Eastern Front – the battle between the Central Powers and the Russian Empire – was equally devastating and consequential, resulting in millions of deaths and divisions that continue to affect the region to this day.

Annamese (colonial troops from French Indochina) disembarking at Camp Saint-Raphael. Over the course of the war, nearly 100,000 Indochinese were deployed in Europe, most as laborers, but several thousand also served in combat battalions. (Bibliotheque nationale de France)

German Vice Admiral Graf Maximilian von Spee’s cruiser squadron, leaving Valparaiso, Chile, on November 3, 1914, following the Battle of Coronel. During the battle, von Spee’s group defeated a Royal Navy squadron commanded by Rear-Admiral Sir Christopher Cradock, sinking two cruisers and killing more than 1,500 men. One minth later, the British tracked down von Spee’s group and started the Battle of the Falkland Islands, sinking or capturing all of the German ships, killing more than 1,800, including the german Vice Admiral. (U.S. Naval Historical Center)

Russian prisoners of war. (Library of Congress)

Cameroon-Company in German Southwest Africa during Word War I. (Koloniales Bildarchiv, Universitatsbibliothek Frankfurt am Main)

Guns removed from the wreck of the SMS Konigsberg. The Germans recovered Konigsberg’s ten 105-millimeter (4.1 in) quick-firing guns, mounted them on improvised field carriages, carried them away, and used them with great success as powerful field guns in their guerrilla campaign against the Allies around East Africa. (Deutsches Bundesarchiv)

Convoy of Spahis, North African light cavalry soldiers, in Francport, France, October 29 1914. (Library of Congress)

A Japanese siege gun brought up for the bombardment of Tsingtao (Qingdao), China in 1914. One of the detachment is receiving orders by telephone from the battery commander. Tsingtao was then a German port, under attack by the British and their allies, the Japanese. (Illustrated War News, 1914)

A railroad bridge near Riga, Latvia, demolished by Russians. German engineers built a makeshift walkway for the infantry. (Der Weltkrieg im Bild/Upper Austrian Federal State Library)

Dead Romanian soldiers near Kronstadt (now Stalin), Romania, in 1916. (Library of Congress)

Russia entered World War I with an army which was massive but badly armed. Russia suffered quick body blows from Germany and went on to one disaster after another. It lost 1,650,000 men killed, 3,850,000 wounded and 2,410,000 prisoners before the 1917 revolution which ousted the tsar and ended Russia’s part in the war. Here reservists, accompanied by relatives, are called up in St. Petersburg as the army was assembled. (AP Photo)

Gallipoli. Soldiers from the United Kingdom, France, Australia, New Zealand, India, Newfoundland, and more engaged Ottoman forces in the Dardanelles in 1915, seeking control of the strait to the Black Sea and the surrounding land. The campaign was disastrous for the Allies, who withdrew after suffering more than 50,000 deaths. (Library of Congress/Central News, The War of the Nations, New York Times)

Anzac, Gallipoli, October of 1915. The “Sphinx” or “Cathedral”. The front tents were occupied by No. 1 Clearing Hospital. (Dr. Herschel Harris/State Library of New South Wales)

One of the few images taken at night during World War I. According to the existing caption it is taken near the Australian lines. The foreground is brightly lit up, with grass and scrub clearly visible. In the background, against a black sky, shell flares criss-cross the sky. (National Library of Scotland)

An Australian bringing in a wounded comrade to hospital. Dardanelles Campaign, ca. 1915. (NARA/US War Dept)

The evacuation of the Bay of Suvla, Gallipoli campaign. (Bibliotheque nationale de France)

Russian cossacks on horseback, ca 1915. (Library of Congress)

Original caption: “Russian Troops in Flight. A remarkable photograph of a scene which followed the recent revolt of Russian troops on the Eastern front. The photo illustrates the first mad rush of the Slavic soldiers at a point of the line, where a cry was raises: ‘The German cavalry have broken through.’ With the raising of the cry the mad stampede started and not one of the runners paused for breath until he had put several miles between him and the firing line.” (National World War I Museum, Kansas City, Missouri, USA)

Chinese labourers at a roll-call in France, during World War I. The coastal towns of China and Hong Kong, where Britain still had some influence, were the main areas from which Chinese labourers were recruited. Over 320,000 were recruited for service with the Allied Forces despite the fact that China was engrossed in her own domestic turmoil. (National Library of Scotland)

Infantry lines North of Jerusalem, near Nebi Samuel, 1917. The Battle of Jerusalem ended up with British forces taking control of Jerusalem from the Ottoman Empire. (Library of Congress)

An aerial view of Jerusalem, ca. 1917. (James Francis Hurley/State Library of New South Wales)

The Church of the Ascension on the Mount of Olives, Jerusalem, January 1918. This image was taken using the Paget process, an early experiment in color photography. (Frank Hurley/State Library of New South Wales)

New Zealand Mounted Riflemen guard a German contingent of prisoners, captured in Palestine, near Jericho, in 1918. (Library of Congress)

The reading of a proclamation at the Tower of David in Jerusalem, December 11, 1917 — two days after the Ottoman Army had surrendered and handed the city over to Allied troops. See this same location today on google maps street view. (Library of Congress/Underwood & Underwood, War of the Nations, New York Times, 1919)

Japanese Red Cross station, operating near Tsingtao in 1915. (Bibliotheque nationale de France)

Young Russian women, having won distinction at the front with decorations, are part of the staff of instructors to inspire new recruits. February, 1918. (Library of Congress)

Annamese (French Indochinese) soldiers clean their guns in the district of the Marne. (Library of Congress/French official Photo, War of the Nations, New York Times, 1919)

The Russians arrive in Marseille. France had asked Russia for help on the Western Front, and Russia responded by sending five Special Brigades — nearly 45,000 soldiers — in 1916. (Bibliotheque nationale de France)

Indian soldiers who served during World War I in France. ca. 1915. (Library of Congress)

A military camp for Australian soldiers in Egypt, during WWI. (State Library of South Australia)

German and Austrian prisoners of war in Russia. A few of the more than 1,800,000 Central Powers forces captured on the Eastern Front during the war. (Library of Congress)

Turkish heavy artillery at Harcira, 1917. Turkish troops with a German 105 mm light field howitzer M98/09. (Library of Congress)

British troops landing to assist Japanese troops in capturing Tsingtao from Germany, in 1914. (Illustrated War News, 1914)

Algerian soldiers in Europe during World War I. (Library of Congress)

An Eastern Front battlefield, littered with the bodies of soldiers (possibly Russian or Serbian), killed in their shallow shell-scrapes. Each man has had his personal equipment removed and his M.91 Mosin-Nagant thrown to the side by advancing Central Powers troops. (Brett Butterworth)

Ready for Russian rush – German machine guns devastated the masses of Russians rushing at them in attack. By the end of the first winter one Russian in four went into the field without a gun. Here German infantrymen aim their machine guns at the Russians from a trench on the Vistula River in Russia, in 1916. (AP Photo)

Soldiers, possibly Russian, going through a barbed wire entanglement. (National World War I Museum, Kansas City, Missouri, USA)

6th Australian light-horse regiment, marching in Sheikh Jarrah, East Jerusalem, on the way to Mt. Scopus, 1918. (Library of Congress)

Reims battlefield with fallen Senegalese soldiers. (Der Weltkrieg im Bild/Upper Austrian Federal State Library)

Slavo-British troops with Lewis guns. These troops were native Russians in British uniforms and commanded by the British. A British officer is on the right of the gunner in the photo. (National Archives)

Austrian soldiers mete out punishment to Russian prisoners. Austria-Hungary took over a million prisoners of war during the Great War, the vast majority being Russians. Using POW labor, the Austro-Hungarians built large POW and civilian internment camps, usually near near major railway lines, which supported the transportation of prisoners and supplies. (Brett Butterworth)

Serbian soldiers man a hilltop trench. (Library of Congress/International News Service, The War of the Nations, New York Times)

A low flying German Fokker E.II 35/15, somewhere on the Eastern Front, ca. 1915. (Brett Butterworth)

Landing of colonial troops in the harbor of Boulogne-sur-Mer, France, on June 13, 1917. Known as the Black Force by General Charles Mangin, French inspector general of colonial troops, these men were relied on by the French army in all the major battles of the war. (British Library)

Gas masks in use in Mesopotamia in 1918. (Bibliotheque nationale de France)

General Kamio, Commander-in-Chief of the Japanese Army at the formal entry of Tsingtao, December, 1914. The Germans had surrendered after a two-month-long blockade and a week-long siege, suffering the loss of 200 men. 4,700 German prisoners were sent to internment camps in Japan, remaining there for nearly six years. (Paul Thompson/New York Times)