http://www.helium.com/knowledge/172874-the-use-of-trenches-during-world-war-i.xml Helium.com > 20th & 21st Century US History > The use of trenches during World War I en-us Copyright Helium.com Mon, 30 Jun 2008 17:35:57 GMT Mon, 30 Jun 2008 17:35:57 GMT