Light discipline is controlling every flame, window and lamp after dark so that none of them shows outside, because the parent article gives a single candle as visible from 1.5 km at night, a campfire from 5 to 10 km and a flashlight pointed at an observer from more than 10 km. Put light only where walls and shields stop it, keep it low and short, and never cover an opening you might need to escape through with anything fixed in place.
Part of Camouflage and Concealment
Light discipline is the habit of limiting and shielding artificial and fire light at night so that a household’s position is not given away across open country.
Darkness Makes Small Lights Visible For Kilometres
At night the eye adapts to the dark and a tiny source stands out. The parent article gives the ranges: a single candle from 1.5 km, a campfire from 5 to 10 km, a flashlight pointed toward an observer from 10 km or more. Those are the parent’s figures; real range depends on haze, cloud and how dark the observer’s own surroundings are, but they show the order of magnitude. A household that thinks of a candle in a window as private has misjudged its reach by orders of magnitude.
There are four sources to manage:
- Fires and glowing embers — see Fire and Smoke Management
- Windows and gaps — any leak around cloth or a door; see Artificial Light Control
- Torches, lamps and lanterns carried outside
- Reflections of moonlight and flares of daylight off glass and metal; see Reflective Surface Management
What You Need
- Heavy cloth, boards or hides for windows, hung so they can be pulled down
- A shielded lamp that can be pointed at the floor
- A red cloth or filter for the rare outdoor torch
- A walk-around at night — the only true test of what leaks
Method: Test From Outside
Step 1: Put out the lights you can do without. Light only where a task needs it, and only as long as it needs it.
Step 2: Close in the rest. Cover windows and gaps from inside, with cloth that overlaps the frame. Use inside rooms and passages that have no outside window as your light zones, as the parent article advises.
Step 3: Go outside at night and look back. Walk round the whole building from every direction and from the viewpoints an observer would use. A thin line of light at a door bottom or a crack at a shutter is seen from far.
Step 4: Point torches down. If you must use a torch outdoors, aim it at the ground and shade it with your body or hand, as the parent article says. A red filter keeps your own night vision.
Step 5: Let eyes adapt. Night vision takes time to develop and is lost to a bright light, as Night Observation explains. A sentry who has just looked into a lamp is blind for a while.
Common Mistakes
- Trusting the cloth until it has been checked from outside. A leak is invisible from inside.
- One bright torch for convenience. A single flash into the sky or toward a ridge is the worst-case signal.
- Total blackout with no way out. The next section is not optional.
- Forgetting the doorway. Opening a lit door at night throws a bright rectangle across the yard.
Safety
Darkness raises the risk of fire and falls, and a covered window is a blocked exit
A blacked-out window is also a blocked escape opening. Anything covering a window someone might climb out of must come down from inside, in the dark, in one movement: a hanging cloth or a propped panel, never a sheet nailed or screwed over the opening. A fire at night is exactly the situation where both facts apply at once. Keep a shielded lamp or other light ready where you can reach it in the dark, so that a household in an emergency can see to leave. Do not seal a room so tightly that a stove or lamp starves of air; see Carbon Monoxide Risks.
What’s Next
- Learn next: Fire and Smoke Management — the biggest light and smoke source
- Combine with: Noise Discipline — light and sound are usually managed together after dark