Final answer:
Persia had a significantly larger army than Greece, often fielding forces with hundreds of thousands of soldiers, whereas the Greeks were heavily outnumbered in their engagements.
Step-by-step explanation:
When comparing the size of the armies of Persia and Greece, Persia had a bigger army and outnumbered Greece significantly. For example, in 480 BCE, King Xerxes I dispatched a vast army that potentially included 200,000 soldiers and 1,200 ships, supported by a navy more than twice the size of that of the Athenians. In contrast, the Greeks were significantly outnumbered, with only a small percentage of Greek cities forming a defensive coalition against the Persians.
Furthermore, during the Battle of Marathon, the Athenians fielded only 10,000 hoplites against a larger Persian expeditionary force. The Persian army was a diverse force, with the Immortals serving as an elite heavy-infantry component. Despite their smaller numbers, the Greek military tactics and the effectiveness of the phalanx contributed to their unlikely victories over the larger Persian forces.