What was the name of Alexander's first major battle against Persia?

Alexander’s first major battle against Persia was the Battle of Granicus. It took place in May 334 BC near the Granicus River in the Troad region of northwestern Anatolia, shortly after Alexander crossed from Europe into Asia.

The Persian army was commanded by regional satraps rather than by the Persian king, Darius III. Alexander launched a bold attack across the river, personally leading cavalry in the fighting. Macedonian cavalry and the disciplined phalanx eventually broke the Persian force, allowing Alexander to begin conquering the Persian-controlled cities of Asia Minor.

Granicus is sometimes confused with Issus or Gaugamela, the two later battles in which Alexander fought Darius III directly. Hydaspes was later still, in India, where Alexander fought King Porus. The victory at Granicus established Alexander’s foothold in Asia and demonstrated the effectiveness of the combined Macedonian cavalry-and-phalanx system.