Although the effectiveness of the once invincible Assyrian army was shown to be greatly depleted by the time of its eventual collapse, the soldiers of Assyria continued to be brave and fierce warriors. Most soldiers at the time would not wear heavy armour, but rather than act as melee troops, would serve as skirmishers. The Assyrian troops were different, since they fought as archers, cavalry and heavy infantry and were useful as front line troops. The Assyrian infantry was specifically trained to engage in hand-to-hand combat. A massive army was assembled by Xerxes in the early 5th century BC. Contemporary estimates place the numbers between 100,000 and over a million. Whatever the number, it was enormous and the Persians summoned troops from all across their realm. Herodotus remarks that Assyrian soldiers were employed in Xerxes' expedition to Greece.