A hundred years ago, on July 28th, 1914 Austria-Hungary declared war on Serbia, this event marked the the start of the First World War. It was the beginning of an era that paved the way for the economic, social, and political changes to come, and mobilized more than 70 million military personnel in one of the largest wars in history. Today we highlight World War I collection in this special edition of the WWI Centennial brought to you by AP Images.

French airship guarding American transports in an undated photo during World War I. Location unknown. (AP Photo)

German airman Manfred von Richthofen, called the "Red Baron," is shown returning from a mission at his squadron's aerodrome at the Front in World War I in 1916. Behind him is the German Cross that marks his plane. (AP Photo)

Ships of the German Fleet, interned by Britain, are shown in Scapa Flow, a bay in the Orkney Islands of Scotland, at the end of World War I in late 1918. Under terms of the armistice, the Germans scuttled their fleet. (AP Photo)

Soldiers returned to the U.S. from France after the Great War march in a homecoming parade in Madison Square, New York City, 1918. In the background is the Flatiron building. (AP Photo)

Ypres Cathedral in Ypres, Belgium, seen from the market square during World War I in an undated photo. (AP Photo)

Air fight between French nobleman De Terline and German Aviator Lt. Freytag. Both machines fell and were shattered to pieces, killing both airmen. Funeral of one of the aviators, July 31, 1916. (AP Photo)

The Indian troops on the bank of the Yser in an undated photo. The only meat served to the Indian troops was goat flesh. Herds of goats accompanied the troops from India, so that hey could eat their favorite dishes. (AP Photo)

The British Grand Fleet under admiral John Jellicoe on her way to meet the Imperial German Navy's fleet for the Battle of Jutland on May 31, 1916 in the North Sea. (AP Photo)

Men of the French Red Cross, transporting a wounded soldier to a first aid station immediately after the battle of Flanders in Belgium in an undated photo. (AP Photo)

German's bringing in Canadian wounded at battle of Vimy, France in 1917. (AP Photo)

In this photo released at his retirement home in Tosny, western Fance, Friday March 3, 2006, Rene Riffaud is seen in either 1917 or 1918. France has rediscovered two centenarian veterans of the 1914-1918 conflict that killed millions, increasing the number of known survivors from five to seven and raising the possibility that there may be others that French officials do not know about. Riffaud was born in Tunisia and joined the Fifth Group of African Campaign Artillery in April 1917. (AP Photo)

Prussian guard infantry in New Field gray uniforms leave Berlin, Germany to entrain for the front, August 1914 during World War I. Girls and women along the line of march hand out flowers to them. (AP Photo)

Lead Image Caption: Photo shows a scene from a Russian battlefield during WWI in 1917. Exact date and location are unknown. (AP Photo)

See more images of the First World War

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