Before the great civilizational clashes at Thermopylae, Plataea and Salamis, there was Pelusium.

The strategically important city on the Nile Delta was where the Egyptians under Pharoah Psametik III made their stand against the invading armies of Cambyses II, the king of Persia, in 525 BCE.

It was a sound decision: Pelusium was heavily fortified, with high stone walls and ramparts. The pharaoh dedicated tens of thousands of men to the city’s defense, lining the ramparts with archers, stone throwers and catapults designed to launch flaming projectiles at the attacking, lightly-armored Persians.

For his part, Cambyses faced the prospect of a long siege or a bloody frontal assault that would cost thousands of lives as his men were tasked with scaling the walls under fire.

But the Persian king knew the Egyptians were not only famously fond of cats, they believed cats were representations of deities.

In a shrewd early example of psychological warfare, Cambyses figured out a way to use felines to his advantage in battle.

Cats were everywhere in ancient Egypt: Goddesses like Sekhmet and Bastet were portrayed as lion- and cat-headed, while Egyptian artists and craftsmen produced statues, rings, pendants and hieroglyphic cartouches with feline imagery. The beloved pets of royalty and other powerful Egyptians were buried in their own elaborate sarcophagi, while regular people mourned the deaths of their family cats by shaving notches in their eyebrows.

Cats are found in virtually every significant ancient Egyptian archaeological site, often elaborately mummified alongside their humans, and Egypt is home to the largest and most enduring cat statue in the world, the Great Sphinx. Not only do weathering patterns show the Sphinx is older than previously thought, it’s believed the Sphinx was originally carved with a cat’s head, then later defaced in the image of a pharaoh. That theory is supported by the fact that the head is disproportionately small compared to the Sphinx’s body, indicating it was carved down from its original form.

Cambyses realized there was a way to turn the Egyptian fondness for all things feline to his advantage: He had his men round up thousands of cats and carry them into battle as if they were just another part of the soldier’s kit along with weapons and armor.

The Egyptians, who were ready to rain fire and death upon the advancing Persians, were distraught upon hearing the distressed mews of the thousands of felines below.

If they opted to fight they would be killing sacred animals who were avatars of some of their most important gods. If they surrendered Egypt would be subsumed into the growing Achaemenid Empire, joining the Medians, Babylonians, Elamites and other once-proud nations in bending the knee to Persia’s king.

They chose the latter, bringing about two centuries of Persian rule in Egypt and leaving the Persians with no remaining obstacles between them and the loose confederation of city-states of Greece.

The kitties, however, would have their revenge against the Persians, for it was a man named Leonidas (“lion”) who led the fabled Spartan warriors to the narrow mountain pass of Thermopylae, where they and a few thousand fellow Greeks held the pass for three days against an invading Persian army that was the largest fighting force the world had ever seen. (Herodotus, the Greek historian prone to patriotic exaggeration, said the Persians were a million strong, drinking entire rivers dry en route to mainland Greece. Modern historians put the number at about 300,000.)

Regardless, the Lion of Sparta and his men inflicted so many casualties on the Persians that the latter’s morale was shattered, and held the pass long enough to give the other Greeks time to muster their army.

When the Persians finally broke through they sacked Athens and rampaged through Attica, until they met an unstoppable force: All of Greece united under the co-leadership of Athens and Sparta, with 50,000 pissed off Spartan Peers leading the defense. The combined forces of the Greek city-states routed the invading army.

We’re sure the Greeks broke out plenty of catnip for their kitties to join in the resulting celebration, and Herodotus just forgot to include that little detail in his histories.