With a gesture, Kourosh gathered the master blacksmiths at the foot of the blast furnace.
The air was still warm from the previous night's heat, and the roar of the bellows never ceased for a moment.
Kourosh stood on a wooden platform and unrolled a scroll of New Persian paper.
This scroll was a copy of the book "Alchemy: The Art of Working with Metals."
With a clear and deliberate voice, he spoke to the crowd that was staring at him with respect and curiosity:
"O great master craftsmen of Pars, you have wrestled with fire and iron for years."
"But today, I will reveal to you a greater secret; the secret of melting iron."
One of the elderly master craftsmen, a man named "Garshasp," spoke with respect but a hint of doubt:
"My lord, iron does not melt."
"We heat it red-hot in the fire, hammer it, and shape it. Only bronze and gold surrender to the fire and become liquid."
This belief was rooted in the thousand-year experience of the blacksmiths.
Kourosh's words sounded like magic to them.
Kourosh smiled.
"Great Garshasp, you are right. With the fire of your furnaces, iron only softens."
"But if we make the fire so powerful that it holds the heart of the sun within it, then even the hardest stones will flow like water."
Using the illustrations and diagrams he had drawn in his book, he explained the technology of the blast furnace.
He explained how, by continuously blowing air, the temperature inside the furnace reaches a point where iron comes out of the iron ore and becomes liquid.
Then he pointed to three key elements.
"For this miracle, we need three things."
"First, iron ore, which is the blood of the earth."
"Second, charcoal, which is the food for our fire."
"And third, this white stone."
He held up a piece of limestone.
"This stone is our magic. It embraces the impurities of the iron like a mother cleansing her child and gives us a pure metal."
These simple and poetic explanations made the complex chemical concepts understandable for the blacksmiths.
Then, he ordered the furnace to be filled, layer by layer.
The workers carefully poured in a thick layer of charcoal first, then a layer of crushed iron ore, and finally, a measure of limestone.
After that, the fire at the bottom of the furnace was lit.
The bellows began to blow with unprecedented force.
Hours passed.
The roar of the furnace grew louder and louder, and its heat was so intense that no one could get near it.
Finally, after hours of breathtaking anticipation, Kourosh signaled to Garshasp.
Garshasp cautiously approached the lower vent of the furnace and, with a long rod, opened the outlet path.
A moment later, a stunning stream of molten, glowing material, golden-orange in color, flowed out of the furnace.
It ran into the sand channels that had been prepared beforehand.
This scene took everyone's breath away.
The blacksmiths and commanders, who had never seen iron in liquid form, were sunk in shock and disbelief.
It was as if they were witnessing the birth of a river of fire.
Kourosh, with a voice trembling with excitement, shouted:
"This is the new blood of our army! This is cast iron!"
"A metal harder than iron, more powerful than bronze!"
"Now, with this metal, we will make swords that will tear through the enemy's shields and spears that will pierce their armor."
He pointed to the sand molds that had been prepared in the shape of spearheads and sword blades.
The molten cast iron was poured into the molds.
After cooling, the first mass-produced Persian weapons took shape.
Arash picked up one of the newly cooled spearheads.
It was heavy, hard, and deadly.
He looked at Kourosh.
This time, in his eyes, there was not just respect for a prince, but an admiration mixed with worship.
He understood that this ten-year-old child was not just a commander, but a creator.
A creator who had harnessed fire itself.
Kourosh gazed at the astonished faces of the commanders and blacksmiths.
They knew that from this day forward, the history of war had changed forever.