The false statement is - Sparta's main strength was its navy.
Unlike the other Greek city-states, Sparta was not as focused on its navy, but instead it was focused on its infantry. The Spartan men were well known throughout the ancient world as the best infantry unit, as excellently organized and disciplined, very strong, skillful, and physically incredibly well prepared. This reputation was in fact with a right reason, because all healthy Spartan men from their very young age were taken away from their homes and were under heavy military training until they reached an age for retiring, and they were indeed the best prepared soldiers of all in the ancient world.
