What Was the Significance of the Victory at Issus for Alexander the Great and the Defeat of Darius?

Alexander the Great fought many battles throughout his life, and all held some significance in his long term plans, but his first battle against Darius, the Persian ruler, was very important for both his campaign, and his men's morale. Although it had a shaky start for Alexander and his men were out numbered, Alexander proved once again his prowess on the battlefield, eventually forcing Darius to flee.
In 333BCE Alexander had won his first major battle in Persia, at Granicus, but he had yet to face the Persian ruler Darius. He and his army marched south through Asia Minor conquering cities, as Alexander travelled through Phoenicia he passed by and conquered the city of Issus. Here he left his sick and wounded to recover, which unfortunately turned out to be a poor decision for those left behind. …