One morning Saddam Hussein decided to invade Iran after a long history of border disputes and fears of Shia Islam insurgency amongst Shiah Iraqis. Saddam simultaneously sent air and land forces to invade Iranian territory and start the longest controversial war of the 20th century.
On this day September 22nd, in 1980, Iraq invades Iran and starts the Iran-Iraq War. This war was often compared to World War I because of the fighting tactics used. The Iraqis utilized large-scale trench warfare, manned machine gun posts, barbed wires across trenches, and extensive use of chemical weapons.
Unfortunately for Iraq, many of their efforts were in vain. After over half a million Iraqi and Iranian soldiers and civilians died, very little changed. All of the Iranian territory that Iraq had gained was quickly taken back, severely damaging Iraqi troops and leaving Iraq with nothing to show for their efforts of conquest. It took 8 years for both sides to reach an official ceasefire agreement.