Hoplites are perhaps best remembered as the main component of the Spartan army. In fact, it was the only type of warrior in the Spartan army.
They formed in a line, with one shield covering most of one man and part of the one next to them. Keeping in a strict, close formation, these shields protected most of the men. The combination of these large shields with long spears made getting to the Spartans, much less fighting them one-on-one, nearly impossible.
The Spartans were by far the most renowned of Greek city-states when it came to martial prowess. The youth of Lakedaimonia were removed from their mothers at the age of seven to be raised in military barracks and trained to be warriors, their primary duty to the state, circumstances allowed by the slave/feudal system imposed by the Spartan elites on the helots of the region who farmed and supported this warrior society.
At 20, a boy became a man and joined the ranks of the Spartan Army, serving until the age of 60. Bravery was prized above all else, and a man who turned and fled in battle was considered to have committed treason, and faced summary execution. Marching off to war with spear, sword, and shield, the women of Sparta would remark to their sons “With it, or on it."
At the height of their power Sparta controlled most of the Peloponnesian peninsula and most of the city-states were subjugated to them and provided additional hoplites to bolster the Spartan battle lines. Tegea was, during the 5th Century BCE their most important ally and their men were afforded the most important place in the battle plans aside from the Spartans themselves.