100 years since World War One

1. 100 years since World War One

2. An American gun crew from Regimental Headquarters Company, 23rd Infantry, fires a 37mm gun during an advance against German entrenched positions. Location unknown. Library of Congress/via REUTERS

3. German prisoners in a French prison camp, circa 1917 - 1919. U.S. National Archives/via REUTERS

4. A gunnery officer writes a Christmas message on a Canadian heavy howitzer during the Battle of the Somme, France, November, 1916. The first Battle of the Somme, one of the bloodiest battles in history, claimed 1,250,000 casualties.

5. Two gas shells explode near Canadian lines during the Battle of the Somme, October, 1916. Library and Archives Canada/via REUTERS

6. Six U.S. soldiers, with five of them wearing gas masks and the other one holding his throat, are seen in an undated photo probably used for training purpose. Library of Congress/via REUTERS

7. American, British, French, and German gas masks. Library of Congress/via REUTERS

8. French cyclists of the Cavalry Corps, on the Champagne Front, eastern France, September 1915. REUTERS/Collection Odette Carrez

9. The sinking of the German armored cruiser SMS Blucher during a naval engagement between German and British dreadnoughts in the North Sea, January 1915. Photo taken from the deck of the British cruiser HMS Arethusa. U.S.

10. French troops from the rear guard eating lunch near Arras, northern France. REUTERS/Collection Odette Carrez

11. Dead German soldiers after a Canadian charge during the Battle of the Somme, France, 1916. W.I. Castle/Library and Archives Canada/via REUTERS

12. Wounded lie in an American field hospital in Auteuil, Paris, France. Library of Congress/via REUTERS

13. Soldiers follow a British Mark IV tank at Ribecourt la Tour, near Cambrai, during the Battle of Cambrai, November 1917. REUTERS/Files

14. Canadian stretcher bearers carry the dead from a battlefield during the Battle of the Somme, July,1916. Henry Edward Knobel/Library and Archives Canada/via REUTERS

15. A photo described as showing French troopers under General Gouraud driving back Germans with their machine guns amongst the ruins of a cathedral near the Marne, France, circa 1918. U.S. National Archives/via REUTERS

16. An American Expeditionary Force doctor tends to an injured American soldier immediately behind the first trench line in France, 1919. Library of Congress/via REUTERS

17. American soldiers getting bowls of chocolate and rolls in the American Red Cross canteen at Toulouse, France, circa 1918. U.S. National Archives/via REUTERS

18. U.S. soldiers of the American Expeditionary Force during a pause in fighting. Location unknown. U.S. Army/via REUTERS

19. American soldiers charging an enemy position. Location unknown. Library of Congress/via REUTERS

20. An Army nurse assists with treatment of a patient. Blood banks were created for the first time during the war to help stabilize the wounded from blood loss. U.S. Army Nurse Corps/via REUTERS

21. L-boat submarines in the Azores. L-class submarines were the U.S. Navy's first attempt at ocean-going submarines. U.S. Navy/via REUTERS

22. German soldiers (rear) offering to surrender to French troops, seen from a listening post in a trench at Massiges, northeastern France. REUTERS/Collection Odette Carrez

23. Canadians return victorious carrying war trophies from Courcelette during the Battle of the Somme, September, 1916. Library and Archives Canada/via REUTERS

24. A U.S. Marine leads training on a shooting range in France. Library of Congress/via REUTERS

25. Field Marshal Horatio Herbert Kitchener (2nd L) meeting French General Albert Baratier (R), on horseback, as French Marshal Joseph Joffre looks on (2nd R), on the Champagne front, eastern France, 1915. REUTERS/Collection Odette Carrez

26. Canadian soldiers leave their trenches during the Battle of the Somme, France, 1916. W.I. Castle/Library and Archives Canada/via REUTERS

27. U.S. Army soldiers playing baseball in France, 1917. Library of Congress/via REUTERS

28. Two American soldiers, Corporal Howard Thompson and James H. White, who were part of a group that killed and captured several Germans in no man's land on March 7, 1918 pose. Thompson holds a pistol taken from a German soldier killed by White.

29. German prisoners carry a stretcher during the Battle of the Somme, November, 1916. Library and Archives Canada/via REUTERS

30. Shrapnel bursts over a reserve trench in Canadian lines during the Battle of the Somme, 1916. W.I. Castle/Library and Archives Canada/via REUTERS

31. U.S. soldiers of the 1st Division advance to seize and hold Cantigny, France, May 1918. U.S. National Archives/via REUTERS

32. 1st Lt. Eddie Rickenbacker, America's most successful World War One fighter ace, poses next to a biplane. U.S. National Archives/via REUTERS

33. Dead German soldiers lie in their trenches during the Battle of the Somme, July, 1916. Library and Archives Canada/via REUTERS

34. Soldiers attending an entertainment show at Suippes, on the Champagne Front, eastern France, 1915. REUTERS/Collection Odette Carrez

35. Soldiers are dwarfed by a shell crater on one of the roads to Bapaume during the Battle of the Somme, October 1916. Library and Archives Canada/via REUTERS

36. Cyclists of the 2nd Battalion, Canadian Expeditionary Force pose at Scottish Lines near Poperinghe, not far from Ypres, France, June 1916. Henry Edward Knobel/Library and Archives Canada/via REUTERS

37. American soldiers of the Machine Gun Battalion, Company G, Second Brigade, gather around an outdoor kitchen in Hermitage, France, March 1918. Library of Congress/via REUTERS

38. A British Mark IV tank falls into a trench at Ribecourt la Tour, near Cambrai, during the Battle of Cambrai, November 1917. Tanks were invented as a means of breaking the trench warfare stalemate. REUTERS/Files

39. U.S. soldiers of Company B, 165th Infantry Regiment, 42d Division, await German patrols near Hazavant, France, September 1918. U.S. National Archives/via REUTERS

40. American soldiers practice throwing hand grenades at enemy positions in Choloy, France, August 1918. Library of Congress/via REUTERS

41. French troops in trenches above Ablain-Saint-Nazaire in the Artois front, northern France, in 1916. REUTERS/Collection Odette Carrez

42. Canadian soldiers return from trenches during the Battle of the Somme, 1916. Library and Archives Canada/via REUTERS

43. French officers inspecting trenches on the Argonne front, eastern France, May 1916. REUTERS/Collection Odette Carrez

44. American troops march down a road in France. Library of Congress/via REUTERS

45. French artillery officers on the phone relaying instructions to adjust cannon fire in a trench on the front line. Location unknown. REUTERS/Collection Odette Carrez

46. German officers captured by Canadians during the Battle of the Somme, October, 1916. Library and Archives Canada/via REUTERS

47. Soldiers and horses amid a destroyed area on the battlefield at Maurepas on the Somme front, northern France, October 1916. REUTERS/Collection Odette Carrez

48. A crowd in Times Square hold up copies of newspapers with a headline about the signing of the Armistice to end the war, in New York, November 11, 1918. U.S. National Archives/via REUTERS

49. U.S. soldiers return to Washington, D.C. following service overseas. Library of Congress/via REUTERS

50. American soldiers of the U.S. Army 27th Division react after arriving in New York City from France on the ocean liner Leviathan, March 1919. Library of Congress/via REUTERS