219 AD, Northern Frontier, Gallia, The Roman Empire.
Lucius eyes snapped open. Standing over him was his father, Cassius, a man whose dignified features now seemed to betray a look of panic.
"Lucius, get up," Cassius urged. "The mine... the iron mine has collapsed. We must go at once to reopen the shafts."
Lucius sat up, rubbing his temples as a headache throbbed behind his eyes.
It had been two weeks since he had first awakened in this era, and the absurdity of his situation still occasionally gave him a migraine.
He was not originally Lucius, the 19-year-old eldest son of a minor Roman equestrian family. In his previous life, he was a 39-year-old senior civil engineer who had graduated at the top of his class from MIT.
He had spent his adult life designing suspension bridges, overseeing infrastructure projects, and mastering the intricate mathematics of structural mechanics and soil geology.
His previous life had ended when a catastrophic crane failure sent a multi-ton steel beam crushing down upon him at a construction site in Seattle.
Yet, instead of eternal darkness, his consciousness had merged with this Roman youth.
Through careful observation of the local politics and the current state of the empire, he had accurately deduced that he was in the Roman province of Gallia Lugdunensis and the year was 219 AD, during the reign of the teenage Emperor Elagabalus.
The iron mine his father was currently panicking over was a recent acquisition. Just two weeks prior, coinciding with Lucius’s transmigration into this body, his family had liquidated nearly all their generational wealth and estates to purchase the mining rights.
It was meant to be their ascendance into immense wealth, a lucrative enterprise to supply the ever-hungry Roman war machine with raw iron. Instead, it appeared their financial future was buried under several tons of collapsed bedrock.
"I am coming, Father," Lucius said.
Within minutes, the household was mobilized. Lucius found himself walking down the uneven roads of Gaul alongside his family.
His mother, Livia, wrung her hands in despair. Beside her was his 17-year-old brother, Marcus, who looked anxious.
Marcus was a boy of literature and poetry. Trailing slightly behind them was his younger sister, Julia, who clung tightly to their mother’s side.
As they walked towards the foothills where the mine was located, they heard the sound of footsteps in the valley.
Lucius paused for a moment as a battalion of Roman infantry marched past them on the main thoroughfare.
Even in a time of crisis, his eyes could not help but dissect the military procession. There were roughly five hundred men marching in strict formation.
They were clad in lorica hamata, the traditional chainmail armor, with a few of the centurions sporting the banded iron of lorica segmentata.
Lucius scoffed as he observed their equipment.
The iron they utilized was brittle and soft compared to the steel he was accustomed to in the 21st century.
If this world were left to its own devices, it would be over a millennium before the Bessemer process or even primitive blast furnaces were invented.
Furthermore, observing the legions reminded him of the instability of 219 AD.
The Roman Empire was entering a period of severe economic inflation and military overreach.
The Severan dynasty was bleeding the treasury dry to pay the legions, and the borders were constantly tested by Germanic tribes to the north.
Supplying iron to these armies was indeed a highly profitable venture, provided one actually had an operating mine.
Shaking away his thoughts, Lucius focused on the task at hand as they finally arrived at the site of the disaster.
Dozens of slaves and indentured workers were running around, coughing on the cloud of dust that still plumed from the mouth of the cavern.
Cassius immediately began shouting orders. "Grab the shovels! Bring the pickaxes! We must clear the entrance and re-shore the tunnels immediately! Our entire fortune is in there!"
Lucius ignored his father’s shouting and walked to the edge of the collapse.
The ancient miners had utilized a primitive room-and-pillar method, but their execution was deeply flawed.
By examining the stratification of the exposed rock, Lucius could immediately deduce the soil mechanics at play.
The bedrock here was composed of fractured limestone and soft shale.
The miners had undoubtedly dug the stopes far too wide in their greed to extract the iron ore quickly, leaving pillars that were far too narrow to handle the compressive stress of the earth above them.
Furthermore, looking at the splintered wooden beams, Lucius noted that the ancient engineers had used a simple butt-joint to connect their vertical posts to the horizontal crossbeams.
It was an incredibly weak load-bearing structure that provided zero resistance against lateral shear forces.
Once the stress distribution shifted, the wooden supports broke, causing the entire roof to collapse.
Marcus, stepping up beside Lucius, looked at the rubble with wide eyes. "Brother... can we fix it? Can we dig it out?"
Lucius picked up a fragment of the splintered timber and tested its density in his hand.
Cassius rushed over to them, grabbing a shovel and shoving it toward Lucius.
"Don’t just stand there, boy!"
"We have to move this rock before the inner veins are sealed!"
"Stop!" Lucius commanded. He tossed the splintered wood aside and pointed to the apex of the collapse, where a jagged fissure had formed in the rock face above the tunnel entrance.
"Do not let a single man touch that rubble, Father," Lucius stated. "If you remove even one stone from the base of that pile, you will alter the resting friction of the debris. The secondary collapse will trigger within seconds, and it will bury every single man standing within fifty paces of this entrance."
Cassius paused. "If we do not provide the iron by the end of the month, we will be destitute. We will be ruined, Lucius."
Livia gasped, covering her mouth with her hands, while Julia buried her face in her mother’s side.
Lucius stared at the mine.
His father was right; they currently had no other source of profit.
The mine could not be reopened right now using the suicidal methods his father suggested. After all, the mountain was holding its breath, waiting for the slightest mistake to collapse the rest of the peak.