<P> The social disruption and widespread violence of the Russian Revolution of 1917 and the ensuing Russian Civil War sparked more than 2,000 pogroms in the former Russian Empire, mostly in Ukraine . An estimated 60,000--200,000 civilian Jews were killed in the atrocities . </P> <P> In the aftermath of World War I, Greece fought against Turkish nationalists led by Mustafa Kemal, a war that eventually resulted in a massive population exchange between the two countries under the Treaty of Lausanne . According to various sources, several hundred thousand Greeks died during this period, which was tied in with the Greek Genocide . </P> <P> World War I began as a clash of 20th - century technology and 19th - century tactics, with the inevitably large ensuing casualties . By the end of 1917, however, the major armies, now numbering millions of men, had modernised and were making use of telephone, wireless communication, armoured cars, tanks, and aircraft . Infantry formations were reorganised, so that 100 - man companies were no longer the main unit of manoeuvre; instead, squads of 10 or so men, under the command of a junior NCO, were favoured . </P> <P> Artillery also underwent a revolution . In 1914, cannons were positioned in the front line and fired directly at their targets . By 1917, indirect fire with guns (as well as mortars and even machine guns) was commonplace, using new techniques for spotting and ranging, notably aircraft and the often overlooked field telephone . Counter-battery missions became commonplace, also, and sound detection was used to locate enemy batteries . </P>

When did world war 1 and 2 begin and end