How good was Hannibal? Does he compare to generals like Alexander the Great and Napoleon in terms of tactical brilliance, or was he a tier below?

As with most ancient history, depends who you trust. Livy is one of the most comprehensive sources we have Rome’s war with Hannibal, which arguably included Hannibal’s greatest achievements. Livy actually compares Hannibal to Alexander the Great in the beginning of his retelling of the war with Carthage. He describes Hannibal as being raised from a young age to be a skilled soldier, and also to possess natural ability and leadership skills. Livy seems to think Hannibal was quite nearly a match for all the great Roman generals of the time. Scipio (Africanus, after the conflict) was the most talented Roman commander during this time, and his victories over Hannibal seem to be hard won. Hannibal also won many battles against Rome, who had the world’s richest and largest army. Usually details like the Roman fighting spirit are attributed for giving Rome an edge over Hannibal.

Comparing him with more modern generals like Napoleon feels nearly impossible—war has changed so much since Hannibal’s time. However, for his time, he certainly seems to have had clever and innovative tactics (using fire, diversions, even spreading misleading rumors to enemy camps). I think it would be fair to put him on par with Alexander or other “Great” generals of the ancient world.