Complex sentence: Despite heavy casualties, the weight of numbers slowly enabled the Carthaginians to advance through the city, and ultimately the last stand of the Greeks took place in the Agora after 9 days of savage fighting.
Split into simpler sentences: Despite heavy casualties, the weight of numbers slowly enabled the Carthaginians to advance through the city. The Greeks began to fall back and ultimately the last stand of the Greeks took place in the Agora after 9 days of savage fighting.