• Millions died as a result of trench warfare---most from non-combat causes.american war cemetery image by Cliff Lloyd from Fotolia.com
  
  Although trench warfare has been around for millenia, its application reached its zenith during the First World War, in which a nearly continuous line of trenches on the Western front stretched over 400 miles, from the French border with Switzerland all the way to the North Sea coast. Modern logistics and transport enabled governments to support armies of millions, and millions of men fought, suffered and died in the trenches from a variety of causes. The large majority of military deaths were non-combat-related.
  
  

Direct Fire

• The First World War was the first war to implement the use of recycle-powered, belt-fed machine guns in large numbers. Many armies deployed specialist machine gun companies and battalions all along the front. The combination of the wide-open landscape on many battlefields and the tendency of armies, especially early in the war, to attempt mass infantry assaults led to a horrendous number of casualties. Additionally, both sides deployed large numbers of snipers and other expert marksmen, equipped with modern scoped bolt-action rifles.
  
  

Artillery

• The industrial revolution allowed both sides to mass-produce artillery and ammunition in a scale never before seen---and to transport it by ship and rail in quantities unimaginable to commanders in prior conflicts. While trenches provided some cover against fragmentation, the large, jagged shell fragments from high explosive rounds caused more traumatic wounds, with greater lethality than rifle fire. High explosive shells could also kill and maim from the concussion effects alone, and the relentless bombardment---sometimes for hours---caused untold psychological damage to trench warfare veterans.
  
  

Chemical Warfare

• Chemical Warfare was illegal under the Hague Convention of 1907. Nevertheless, World War I saw the introduction of chemical warfare on an unprecedented scale. The preferred chemical agents were chlorine gas, mustard gas and phosgene, a nerve agent. The U.S. Army's Command and General Staff College estimates total fatalities due to chemical warfare in WWI to be over 85,000, with over 1.1 million wounded---many of them with permanently debilitating lung injuries.
  
  

Infections

• During WWI, medicine was backward, by today's standards, and transport to critical care facilities was limited. Most medical treatment had to occur at the front, under horrific sanitary conditions. Penicillin and other antibiotics were unheard of at the time, and huge numbers of troops perished of infections like gangrene as a result of wounds---even flesh wounds to legs and arms that would be easily treated today. Abdominal wounds were almost always lethal.
  
  

Disease

• Terrible sanitary conditions and close quarters living created a fertile environment for many lethal illnesses, such as cholera, dysentery, malaria, scarlet fever, diptheria and influenza, which spread from the trenches to inflict a raging worldwide epidemic that killed more than 50 million people in 1918.
  
  

Environmental and Hygienic Conditions

• Poor drainage in the trenches and the inability of soldiers to reach high ground (for fear of being shot) resulted in widespread trenchfoot---a debilitating fungal infection that led to an inability to walk. In advanced cases, trenchfoot could lead to gangrene, amputation, and in a world without antibiotics, death.