<P> Another example of trench warfare after World Wars I and II was the Iran--Iraq War, in which both armies lacked training in combined arms operations . Tactics used included trench warfare, machine gun posts, bayonet charges, use of barbed wire across trenches and on no - man's land, Iranian human wave attacks, and Iraq's extensive use of chemical weapons such as mustard gas against Iranian troops . </P> <P> Although mainly a siege, it was not unusual to find an extensive trench system inside and outside the city of Sarajevo during the siege of 1992--1996 . It was used mainly for transportation to the frontline or to avoid snipers inside the city . Any pre-existing structures were used as trenches; the best known example is the bobsleigh course at Trebević, which was used by both Serb and Bosniak forces during the siege . Another example of trench stalemate was the Eritrean - Ethiopian War of 1998--2000 . The front line in Korea and the front lines between Pakistan and India in Kashmir are two examples of demarcation lines which could become hot at any time . They consist of kilometres of trenches linking fortified strongpoints and in Korea surrounded by millions of land mines . </P> <P> A recent example of trench warfare occurred in the War in Donbass, in which Pro-Russian rebels fought the Ukrainian government . More than 6,000 people were killed in a year of combat . To consolidate and defend their territory and / or gains, government and rebel forces have dug trenches and have initiated warfare reminiscent of World War I, such as open trench warfare with troops staying in and fighting from trenches for months at a time . Despite the Minsk peace agreements low - intensity firefights and combat patrols continue to this day . </P>

What were the four types of trenches used by the allies in world war 1