Friday 1 July 2016 marks the 100th anniversary of the Somme Offensive – one of the bloodiest battles in history. The Allies had prepared for the battle by bombarding the enemy for a week in late June 1916. However, the bulk of the German forces hunkered down in deep trenches and lay in wait.

The first day of July was a disaster for the British Army. Thousands upon thousands of men were sent over the top, charging into no-man's landed armed with bayoneted rifles, but they were mowed down by German machine guns. Around 20,000 British soldiers were killed on the first day alone. The French, whose attack was less expected, gained more ground.

On 14 July, the British managed to overrun the Germans' second defence system, but failed to exploit their advantage. Their advance was slow, and they paid the price of heavy losses for the little ground gained. For nearly five months the fighting raged on in a battle of attrition along a 15-mile front.By the time the battle ended in mid-November 1916, British, French and German casualties totalled more than 1,250,000 men.

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1 July 1916: British troops go over the top on the first day of The Big Push on the SommeMorgan-Wells/Hulton Archive/Getty Images
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French soldiers of the 67th Infantry Regiment are seen in trenches on the Somme frontCollection Odette Carrez/Reuters
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1 July 1916: Canadian troops prepare for the charge over the top at the Battle of the SommeHulton Archive/Getty Images
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A heavy shell exploding during the Battle of the SommeHulton Archive/Getty Images
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Trenches of the 11th Cheshire Regiment at Ovillers-la-Boisselle in July 1916. One sentry keeps watch while the others sleepErnest Brooks, Imperial War Museums
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A British serviceman covers a dead German soldier in a trench during the capture of OvillersHulton Archive/Getty Images
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Shrapnel bursts over a reserve trench in Canadian lines during the Battle of the SommeW.I. Castle/Library and Archives Canada/Reuters
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Dead German soldiers lie in trenches that were demolished during the Battle of the Somme in July 1916Canada. Dept. of National Defence/Library and Archives Canada/Reuters
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French soldiers are pictured in a trench south of Thiepval, on the Somme frontCollection Odette Carrez/Reuters
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An early model British Mark I tank, named C-15, is pictured near Thiepval on 25 September 1916Imperial War Museums
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Gas-masked soldiers from the British Machine Gun Corps man a Vickers machine gun during the first battle of the SommeGeneral Photographic Agency/Getty Images
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The 39th Siege Battery artillery in action in the Fricourt-Mametz ValleyHulton Archive/Getty Images
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A dump of 18-pounder shell cases used in the bomdardment of FricourtImperial War Museums
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Canadian stretcher bearers carry the dead from a battlefield during the Battle of the Somme in July 1916Henry Edward Knobel/Canada. Dept. of National Defence/Library and Archives Canada/Reuters
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A German prisoner helps wounded British soldiers make their way to a dressing station near Bernafay Wood following fighting on Bazentin Ridge, on 19 July 1916Ernest Brooks, Imperial War Museums
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A British-built SS (Submarine Scout) class airship is launched on a reconnaissance flight over the Somme in August 1916Topical Press Agency/Hulton Archive/Getty Images
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Two gas shells explode during the Battle of the Somme in October 1916Reuters
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British soldiers are pictured standing near their machine guns on the Somme frontCollection Odette Carrez/Reuters
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A mobile anti-aircraft gun used by French forces on the Somme, circa 1916Keystone/Getty Images
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German troops advance across open ground at Villers-Bretonneux during Germany's last major effort to secure victory on the Western FrontHulton Archive/Getty Images
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French soldiers stand in German trenches seized after being shelled on the Somme front in 1916Collection Odette Carrez/Reuters
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Canadians return victorious carrying war trophies from Courcelette during the Battle of the Somme in September 1916Canada. Dept. of National Defence/Library and Archives Canada/Reuters
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Wounded men are dressed in a trench during the Courcelette operation of the Battle of the Somme on 15 September 1916William Ivor Castle/Canada. Dept. of National Defence/Library and Archives Canada/Reuters
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October 1916: British artillery men transport a gun through the SommeTopical Press Agency/Getty Images
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October 1916: A deserted German trench on the Somme littered with personal belongings and empty tinsTopical Press Agency/Getty Images
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Soldiers and horses are seen at a destroyed spot on the battlefield at Maurepas in October 1916Collection Odette Carrez/Reuters
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An image of Christ on the cross is seen at a grave by a tree at Fricourt in October 1916Collection Odette Carrez/Reuters
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A German cannon buried under uprooted trees in Louage Wood is pictured on 10 October 1916 during the offensive on the SommeTopical Press Agency/Hulton Archive/Getty Images
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German soldiers' graves are seen at Thiescourt on the Somme front lineCollection Odette Carrez/Reuters
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German officers captured by Canadians are seen during the Battle of the Somme in October 1916Canada. Dept. of National Defence/Library and Archives Canada/Reuters
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German prisoners carry a stretcher during the Battle of the Somme in November 1916Reuters
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An officer writes a Christmas message on a Canadian heavy howitzer during the Battle of the Somme in November 1916Reuters

The First World War, also known as the Great War, began on 28 July 1914 and lasted until 11 November 1918. It originated in Europe but became a global military conflict that killed more than 16 million people and changed the nature of warfare. On land, sea and in the air, 1914-18 was a war of new and experimental technology - technology that would increase casualty figures beyond the worst nightmares of previous conflicts. Between 1914 and 1918, 400-million artillery rounds were fired in the narrow battlefield straddling France and Belgium.

World War One saw the introduction of many firsts in technological, scientific and societal innovations. Tanks were invented as a means of breaking the trench warfare stalemate. Chemical weapons in the form of deadly poison gases were used for the first time, leading quickly to the development of the first gas masks.

After initial success, the German army faced exactly the same problems as the Allies had earlier in the war and overstepped their abilities. The central powers quickly collapsed - the Ottoman Empire crumbled in the Middle East, and the Austro-Hungarian empire disintegrated into separate states after Italian victories in 1918. On the Western Front, an allied counter-attack, including the Americans, prompted the Germans to ask American President Wilson for an armistice. The German government itself disintegrated and an armistice was signed.

As wild celebrations broke out in London and Paris on 11 November 1918, Germany stood defeated, even though its forces still occupied much of Europe. After the treaty of Versailles, Germany remained a sovereign nation, but with her navy impounded, much of her weaponry handed over, the Rhineland seized, and facing an enormous reparations bill. The seeds of the Second World War had partly been sown.