What are some of the worst decisions in human history? I'll go first: 1. Xerxes' invasion of Greece 2. The Romans' decision to overrule caution and give battle at Cannae 3. Crassus' invasion of Parthia 4. The Roman decision to betray the Goths in 410, right before they sacked Rome 5. The crucifixion of Jesus 6. The decision of the Umayyads to kill the family of the Prophet at Karbala 7. The Khwarezmian governor of Otrar's decision to provoke the Mongols by beheading the Mongol emmisaries 8. Napoleon's invasion of Russia in 1812 9. The Ottoman Empire's decision to enter ww1 on the side of Germany 10. The decision of Germany to allow Hitler into power in 1933 Those are just a few from the many possibilities. What are your top ten worst decisions of history?