12. The Iran-Iraq War (1980-1988)
The Iran-Iraq War began on September 22, 1980, when Iraq launched a full-scale invasion of Iran, initiating nearly eight years of intense conflict. Despite the extensive military engagement and significant casualties, neither country issued a formal declaration of war. The conflict resulted in an estimated 500,000 to 1 million deaths, with Iran bearing the greater share of the casualties. (en.wikipedia.org)
