Edited sentence: If Leonidas had not made that brave stand at the Pass of Thermopylae the Greeks most definitely would have been destroyed, and all their contributions to the  world today, may not have survived.Leonidas was a hero, he held back the Persians long enough for Greece to ready for their attack.Luckily though they had time to ready for the Battle of Salamis where the Persian King Darius expected a victory and instead watched a horrible defeat of his Navy