Anno Domini 1800.

It was the latest installment in the critically acclaimed Anno series, a masterpiece of city-building and strategy. From my current perspective, its release lay four hundred and five years in the future—a realization that sent a prickle of existential dread down my spine. Still, the game was a worthy reference. I had poured hundreds of hours into it in my past life, enamored by the meticulously rendered 19th-century setting.

In this game, where one meticulously expands their city across the 1800s, ‘navigation’ serves as the primary means of interacting with other powers. The vessels used spanned the 19th and early 20th centuries, making them the perfect models to study. Our own steam technology sat in that awkward, transitional period between the late 18th and early 19th centuries.

While the game wasn’t an educational manual and certainly didn’t provide detailed blueprints, it offered a visual catalog of what ships existed during that era.

“A waterwheel on both sides of the hull?” a shipbuilder asked, leaning over my sketches.

“Precisely,” I replied, tracing the mechanism. “The central engine will drive the axle, turning the wheels to churn the water and provide propulsion.”

That simple explanation sufficed. Sometimes, a general form is enough to deduce the underlying principle. The paddle wheeler was a vessel whose function was entirely intuitive; one only had to look at the massive wheels mounted on the exterior to understand how it moved. By rotating those wheels and pushing against the water, the ship gained its thrust.

Even as a layman, I could see why this design eventually faced extinction. Compared to the compact, elegant screw propeller, these wheels were gargantuan and cumbersome. Furthermore, in rough seas or foul weather, the wheels would dip too deep or lift too high as the ship tossed, halving their efficiency.

The screw propeller was, in every conceivable way, the superior structure. If it weren’t, I would have seen paddle wheelers in the 21st century outside of toys or historical replicas.

However, I also understood why the early pioneers of steam chose this method. The structure was undeniably simple. Instead of finding a place for rows of oarsmen, they simply mounted wheels. Moreover, because the wheels only needed to be partially submerged to function, the ship maintained a shallow draft. This made them ideal for navigating shallow waters. If they were difficult to handle in the open ocean, we would simply restrict them to rivers and coastal routes.

I pointed to the Great Eastern and the Salvage Ship—special vessels from Anno 1800—and addressed the shipbuilders. “Ignore the ironclad plating for now; focus on the silhouette. We will mount massive paddle wheels on the sides, but we must also retain masts and sails in case the fuel runs dry.”

The men fell silent, scrutinizing the drawings.

“What do you think?” I prompted.

“It’s fascinating,” one mused, his eyes brightening. “Wheels on the sides… it might actually work.”

Their reception was positive. We had taken another step toward constructing the first steamboat in human history.

“Wait, this ‘salvage ship’ here… it has a crane attached,” another noted.

“Correct.”

“What is its purpose?”

“Construction,” I answered simply. “We are building breakwaters and bridges. We need a dedicated vessel for underwater engineering. That crane will be used to move these.”

I revealed a new set of sketches.

“These… they look like sea urchins that Plato tried to abstract,” Harriet remarked, peering at the shapes.

“Your descriptions are far too high-brow, Harriet,” I teased. “Stop the chatter and let’s begin the experiment. Pour the water into the breakwater model.”

I was introducing the Tetrapod.

***

The Tetrapod.

It is a four-legged, tetrahedral concrete structure.

In the modern world, you can often see these jagged shapes interlocking along the coast to form breakwaters. I knew the name and the general look, though I didn’t know the exact physics of why they outperformed traditional breakwaters. My logic was simple: if the modern world used them, they were probably superior. Otherwise, I would have stuck to the traditional method of stacking rocks.

The advantages of the Tetrapod were numerous. Traditional breakwaters made of gravel and boulders were easily swept away by powerful waves, requiring constant and expensive maintenance. In contrast, Tetrapods interlock with one another, creating a stable, porous structure that is far less likely to collapse.

Their ability to dissipate wave energy is also vastly superior. Because of their shape, they create numerous gaps that allow seawater to flow through, effectively neutralizing the force of the waves without breaking the structure itself. Of course, those same gaps tend to swallow fishermen who venture where they shouldn’t, but that was a separate issue.

In terms of sheer effectiveness, they were several times more efficient than traditional mounds. They were perfect for the unpredictable currents and rough swells of Pamlico Sound, a fact Harriet confirmed through her small-scale experiments. If we had tried to pour dirt and gravel into those waters, the currents would have reclaimed the materials in an instant.

Furthermore, Tetrapods were easy to mass-produce. The ironworkers on Roanoke Island were already preparing massive molds, three to four meters in height. Once we poured the concrete and stripped the molds, we would have a finished Tetrapod. This ability to maintain consistent size and quality gave them a significant edge over quarried stones of varying shapes.

And for our specific situation in the Virginia community, there was one more hidden benefit.

“Is the concrete supply holding up?” I asked the supervisors. “How are the mixing ratios?”

“Yes, Nameless One,” they replied. “We are gradually perfecting the proportions of the materials.”

The benefit was the concrete itself. By the 17th century, the use of concrete was beginning to see a resurgence, but it was hardly a standardized industry. Neither the local technicians nor I knew exactly which ratios would produce the strongest or most durable results. The Tetrapods served as our experimental subjects—since they were essentially consumables, ruining a few during the learning process wouldn’t be a disaster.

As research into concrete began in earnest, we also broke ground on the first road in Chesapeake.

“How wide should the road be in feet?” a clerk asked, quill at the ready.

“We will use the metric system,” I stated flatly.

I was the ‘Angel of Units,’ and I was not about to let anyone waste time on ‘imperial’ nonsense.

***

In this era, there was usually no reason for a road to be exceptionally wide. How large could a wagon be, and how much traffic could there possibly be to justify anything resembling a modern highway?

“Shall we make it… this wide?” a surveyor suggested, marking a modest distance.

“Not nearly enough!” another countered. “It must be wide enough for four of Lord Nemo’s ‘Porters’ to pass side-by-side!”

In our community, things were different. Our wagons were already as wide as the modern Hyundai Porter trucks I had brought from the future. The very first paths in the colony had been carved by the tires of those Porters and Damas vans; thus, the road width had been determined by the vehicles, rather than the vehicles being limited by the roads.

The second reason was slightly more absurd: the people admired the Porters so much that they began mimicking their dimensions for their own horse-drawn carriages. It sounds ridiculous, but it was the truth.

“Then, following the Porter’s width, shall we go with ten feet…?”

“Three meters,” I cut in. The yard-pound-foot heresy would find no sanctuary in my church. Once I had purged the ‘heathen’ units, everything became clear. The metric system was truly divine.

We decided on a road width of twelve meters. While it seemed excessively wide for the 17th century, I was looking toward the future. I wanted these roads to remain functional even when automobiles and carriages eventually shared the pavement by the dozens.

We couldn’t link Chesapeake and Croatoan immediately—the bridges had to be built first—so for now, we focused on the infrastructure around Chesapeake, which had grown into a city of tens of thousands. We planned to extend the roads along the coast to the west and north, while also paving a main artery from the harbor to the heart of the city.

Wait… these are basically the Seoul Subway Lines 1 and 2, I realized with a wry smile. I suppose Korea will always be the home of my heart.

Paving the roads didn’t require massive amounts of concrete yet; we were too busy with the breakwaters. Instead, we followed a simpler method: digging shallow trenches and filling them with decomposed granite. This ensured proper drainage and a relatively level surface for travel.

The mining operations provided an abundance of sand and gravel, which were either used for the roadbeds or as aggregate for the concrete. The concrete was then cast into Tetrapods, which were loaded onto the soon-to-be-completed salvage ships to build the breakwaters. As the waves were pushed back, the roads advanced.

Simultaneously, the coal from the mines fueled the ironworks, the cement factories, and the steamboats, accelerating the entire cycle of development. Everything was interconnected.

Even those who had previously remained on the sidelines of the monasteries, claiming they weren’t suited for ‘manual labor,’ flocked to join these public works. The new immigrants, though initially bewildered, followed suit once they saw the fervor of the community.

The community was functioning remarkably well. As the cement factories grew and our knowledge of casting and curing concrete matured, we would soon be able to build massive structures out of the material. And once I revealed the secret of ‘reinforced concrete’—the miracle that steel and concrete share the same coefficient of thermal expansion—the world would truly be moved to tears.

Everything was running smoothly, bolstered by future technology and knowledge. In truth, I hadn’t done all that much. I merely had to mutter a few vague memories of ‘how things used to be,’ and the people would take those fragments and run with them, achieving incredible efficiency.

I was beginning to understand how haphazard the process of invention and improvement actually was. Take Edison, for example, who supposedly tested seven thousand different materials for a lightbulb filament. If I were to compete with him, I would simply go straight to bamboo charcoal or tungsten, because I already knew the answer.

Armed with the ‘answer key’ of history, we could advance at a blinding pace. In the world inside my head—the world that had not yet come to pass for them—people had already failed and succeeded tens of thousands of times over the centuries.

And that knowledge… was mine alone.

I was the only one who could read the educational comics, the books in the study, and the detailed catalog from Immortal Kingdom. Before questions of right and wrong, I pondered how broadly one person’s knowledge could change the world. There are limits to what a single traveler from the future can do. I am no omnipotent genius; I cannot produce results beyond the fragments of knowledge I possess. Even if I master every secret in my study, those technologies will wither and die if I cannot find a way to implement them through others.

I felt this limitation acutely during this development project. What if I shared the principles of the screw propeller with the shipbuilders and asked for their continuous research? Would its development truly remain impossible?

I cannot achieve greater things alone. It is simply not possible.

Our community has been protected by a technological edge over the outside world—whether it was the 21st-century artifacts I brought or the results of the future knowledge we applied here. Lexan plating, modern muskets, war tractors—these are the pillars of our survival. If the tractors vanished from our fields, our entire industrial base would collapse in an instant.

That advantage has allowed us to stand firm against the waves of history. We will always need technological breakthroughs; we must always stay ahead of the curve to remain safe.

And if I cannot guarantee that through my own struggles alone? If the breakwater protecting this community should one day crumble before a wave too large to handle?

I reached a conclusion.

Knowledge must be shared.