The World War I was a significant turning point in the Twentieth century." The roles of Wilson, Clemenceau and Lloyd-George helped structure the peace agreements. Some historians have criticized the Treaty Of Versailles as a failure and as the signal event that laid the foundation for World War II. .
Twenty-seven countries on five continents were involved in World War I. This war was also called the Great War. New weapons and new methods of warfare were developed during World War I that dramatically affected the war. World War I was the bloodiest and most costly of all the previous wars. World War I was different from previous wars because of the new types of weapons and methods used on the battlefields, in the skies, and on the seas. World War I was different from previous wars because of the types of weapons and the methods of warfare used. Soldiers first saw the use of tanks, submarines, trench warfare, hand grenades, long-range field guns, air warfare including bombers and airships called zeppelins, and poisonous mustard gas. Because of the new technology in warfare, World War I took the lives of twice as many members of our armed forces as all the previous major wars put together. The British army first established the use of tanks, a new weapon in warfare. The Germans, in turn, developed new weapons to deal with the tanks, which included field guns. World War I marked the beginning of chemical warfare in which clouds of poisonous mustard gas contributed to the casualties of the war. Unlike previous wars, World War I was fought on the sea and in the air. This was the first war in which airplanes and zeppelins were used. At the outbreak of the war, each army had several hundred planes. The Germans used the zeppelin for observation and for bombing raids. The submarine came into use for the first time on a large scale during World War I. The Germans speeded up production of submarines in an effort to control the bottom of the sea.