Daniel 8:6,7

‘And he came to the ram which had two horns, which I saw standing before the river, and ran on him in the fury of his power. And I saw him come close to the ram, and he was full of rage against him, and smote the ram and broke his two horns. And there was no power in the ram to stand before him. But he cast him down to the ground and trampled on him. And there was none who could deliver the ram out of his hand.'

Alexander's swift approach and savage attack defeated the Persian army which came out to oppose him, and he then overran Syria and Palestine and finally defeated the Persians once and for all at the battle of Gaugamela, near Nineveh in 331 BC. The contrast between the one horn of the he-goat (thus a visionary goat, for goats have two horns) with the two horns of the ram, emphasis the dual nature of the Medo-Persian empire. This duality is constantly emphasised as we have seen.