This story, another famous anecdote about the Spartans’ bravery, is from the time of Philip of Macedon (382-336 B.C.), who forcibly unified most of Greece’s cities.
"Long ago the people of Greece were not united, as they are today. Instead there were several cities and states, each with its own leader. King Philip of Macedon, a land in the northern part of Greece, wanted to bring all of Greece together under his rule. So he raised a great army and made war upon the other states, until nearly all were forced to call him their king. Sparta, however, resisted.
"The Spartans lived in the southern part of Greece, an area called Laconia, and so they were sometimes called Lacons. They were noted for their simple habits and their bravery. They were also known as a people who used few words and chose them carefully; even today a short answer is often described as being 'laconic.'
"Philip knew he must subdue the Spartans if all of Greece was to be his. So he brought his great army to the borders of Laconia, and sent a message to the Spartans.
"'If you do not submit at once,' he threatened them, 'I will invade your country. And if I invade, I will pillage and burn everything you hold dear. If I march into Laconia, I will level your great city to the ground.'
"In a few days, Philip received an answer. When he opened the letter, he found only one word written there.
"That word was 'IF.'"
--The Book of Virtues
Edited, with Commentary, by William J. Bennett
This story reminds me of the 101st Division (U.S. Army) in Bastogne, Belgium in December 1944. The 101st Division was surrounded by the German Army and the Germans asked for their surrender. General McAuliffe sent them a written reply: “NUTS!”
Bastogne: The First Eight Days