War and conflicts have been in the world since the dawn of civilisation. These conflicts have shaped our history, civilisations, communities and lives. Past research focused on the socio-economic foundations of the conflicts as well as the geopolitical implications. But the impact of war and conflicts on the environment is still obscure and less researched. With the advent of modern technologies, the environmental footprint of the wars is massive and most of the time, undocumented. This chapter addressed this research gap by noting the major wars, conflict and their environmental impacts. The major conflicts span the historical landscape from the first industrial era to the fourth industrial era. The major conflicts covered in this chapter are, Napoleonic Wars (1803–15), War of 1812 (USA vs Britain), the Crimean War (1853–56), The Sepoy Mutiny (1857), American Civil War (1861–65), Franco-Prussian War (1870–71), First Boer War & Second Boer War (1880–81 & 1899–1902), Spanish-American War (1898), Russo-Japanese War (1904–05), World War I (1914–18), Russian Revolution & Civil War (1917–22), Chinese Civil War (1927–49), Spanish Civil War (1936–39), World War II (1939–45), Korean War (1950–53), Vietnam War (1955–75), Six Day War (1967), Soviet Afghan War (1979–89), Iran- Iraq War (1980–88), Falklands War (1982), The Gulf War (1990–91), and Yugoslav Wars (1991– 2001). These major wars are considered and analysed for any available information on ithe environmental impact.