The section of the wall we guard doesn’t look like much. Other places try to dress up theirs, make it look like something it’s not. Out here, we always think that things should look exactly as they are whenever possible, so we’ve never tried to dress it up. It’s the wall, that’s all. And it keeps us alive.

This side doesn’t impress, and here I’m not discussing aesthetics. It’s only forty feet high. However, were you to climb up and look down, on the other side you would find it’s five hundred feet to the valley below.

I can’t tell you anything about the engineering that went into building it. It had been in place for two hundred years before my grandfather was crawling, and that’s only what they say. No one knows for sure. What we do know for sure is that it’s all that separates us from the were-creatures that make their home outside the wall. They would like nothing more, when the moon is bloated and full and hanging in the sky like a cancer, than to kill us, each and every man, woman and child, in our beds. So our lives revolve around this wall.

During the rest of the month, you can be lowered down to the valley floor in safety. Indeed, during the time of blank moon, we send parties to ensure our catapults and trebuchets have destroyed any devices the creatures built. It’s said they’re becoming smarter as the years wear on and I’m inclined to believe this. Usually it takes a couple of nights for the attacks on the wall to begin in earnest, but one month, fifty miles north of here, the first night erupted in balls of fire being rained down upon the township behind the wall.

The realization was twofold. The first was that they must have built the machines the previous month and then hid them, knowing we destroy whatever we find standing when they return to their true forms. The second…was fire. How in God’s name had they come upon fire?

The attack was beaten back, though with some cost of life and property, but it proved that they were, even dimly, beginning to remember one month to the next and not forget what had happened between their transformations. And thus, could create long-term plans.

When the sun goes down on the first day–the first of eight, though I hear long ago it had been half that number–the men of the townships along the wall stand watch and wait for the attacks to come. And they do, sooner or later. We work in shifts, twelve hours of darkness on, twelve hours of daylight off. And life in the townships stops. Our women and children barricade themselves in their homes and will not let us in until we can say a passphrase chosen beforehand. My own wife, heavy with her first child, sits at home and waits for me.

We cannot spare a single man who could make the difference. No matter the profession, from the township’s doctor Marc to farmers like my best friend, Thalm, all must take their stand. If any of the creatures somehow make it over the wall, it would be nearly impossible to stop them. For once the full moon is up, every animal in the valley, were-creatures all of them, look just like us. They will even steal the face of someone they have seen. I’ve watched through a spyglass as a mask badger transformed into the spitting image of Rorie, a man who fell from the wall into the valley during the previous month’s assault. Then we poured hot oil down on the naked, pink, horrible thing before it could fully reacquaint itself with its new center of gravity. It shrieked as it died…the only sound those things can make. The passphrases keep our families safe if any of the creatures make and break for the township, wearing a human face. They can only scream and howl and batter at the doors for entrance. Or, even worse, pass on their disease to our livestock and ruin our food supply.

This is how it has always been. Thalm and I began our watch with our fathers at the age of eight. We quickly learned to work the crossbow, the catapult, the trebuchet, the firethrowers and the oil. We had our wounded, yes, but our township had never been threatened directly by the creatures. We and the wall had always stopped them. Thalm and I had stood together for nearly twenty years.

The last attack was especially troubling. The creatures had used catapults before—this was nothing new. But on the second night, they began using a different sort of ammunition. Themselves.

When the first of them hit the wall about twenty feet below the fence with a sickening, wet thud, we at first thought nothing of it. We hadn’t seen what had hit. When we looked down and saw the impact point, soaked in blood, we knew something bad was happening.

During that point they had adjusted their aim and fired again. The first one over the fence cut itself on the leg but managed to land on all fours, cracking its chin open on the stone as it did so. These things are remarkably hardy dopplegangers of humans, but as I looked down at the thing that was looking up at me, I felt my heart stop in my chest.

I was looking down at a feral, grinning version of myself. They had clothed it in a shoddy rendition of my own garb and it was wearing my face.

Driven by pure instinct and revulsion, I kicked it right on the point of its wounded chin and Thalm stabbed it with the head of its spear. It shrieked as it was pierced and, convulsing and foaming, died there on the concrete.

They had created a spyglass of some sort. They had to have. They cannot see us up here. The only reason they knew Rorie’s face was he had fallen. But they were trying to send over dopplegangers that could blend in long enough to infect the animals and kill as many of us as they could. God protect us.

And they kept hurling themselves. We killed three more versions of myself, and countless others from the people on the wall. Their aim was uncanny. And we had to send the majority of us into the yard below our side of the wall to slay those creatures who overshot the top. Thalm and I stood our ground on the top of the wall, even as a large boulder crashed through the fence, tearing down a large section of it so that the creatures could sail over easier.

When the moment I had been waiting for for over eight months occurred, I slipped into a mode that was like swimming through a dream. I barely was aware of what was happening. The first duplicate of Thalm careened onto the wall between the two of us. Thalm stuck the head of his spear through his double’s throat and the thing went down. And I fired my crossbow—not into Thalm’s heart, but as close as I could manage. He dropped to his knees, and the look on his face was something I will never forget. It wasn’t shock, it was almost acceptance.

I leaned over to him and whispered in his ear the passphrase he had used at my door I don’t know how many times, “Let us be glad for comfort.” Then I added, “She was mine, Thalm. She was mine.” And then, I pushed him over the wall. I heard him bounce twice on the way down.

The attack ended. In the chaos, no one had seen. When they asked what had happened, I merely pointed to the missing section of fence and shook my head sadly. It was accepted. These things happened when you were defending your home.

And so it continues. Our family will have a child, and the creatures beyond the wall will drop litters of their own that wish to kill that child. Humans and animals who think they are humans alike, all our lives revolve around this wall. And while the moon is diminished, we are not, so we can rest. All of us.