The lantern line is nine emitters on two risers, and I can see all nine. That is the whole of my job and most of the Concord's doctrine: see first, decide once. The risers are basalt steps two hundred metres apart, wet, black, faster on Glide than they look and slower on the climb than anyone expects. Between them is the flat. Nothing crosses the flat unseen, which is why nothing tries.
Twelve minutes into the action the Covenant raid kills lantern six. I log it. A Vector Cannon from the third terrace, the limit of its range, a good shot. The Engineer asks whether to replace it and I say no, because a replaced lantern is a lantern they know about, and because six was the one I expected them to kill. Eight still reads. Eight sees the same riser from the other side.
The crossings begin at fourteen minutes. Three fast ones on the upper riser: Rangers, above the Break, going somewhere loudly. I classify them and pass them to the interceptors and do not think about them again. The Covenant does not attack with Rangers. The Covenant attacks with a Bulwark from a ridge, and everything before the Bulwark is a way of getting a beacon set.
So I watch for slow.
Nine seconds after the third fast crossing, lantern eight reports something on the lower riser at a walking pace, coupling high, no Burn. On the display it is a foundry worker. On Tessel there are no foundry workers. I mark it infiltrator, Traction, wrong paint, and give it to the jammer with a point on the flat two hundred metres short of the wall, and the jammer spoofs the beacon before the beacon has finished being set. From the infiltrator's side nothing is wrong. His mark is transmitting. The mark is mine.
At sixteen minutes the Covenant battery lays its solution and I watch the first salvo come off the ridge as arcs, eleven of them, into the flat, where they achieve a great deal against basalt. Datum, in the counter-battery position on the lower terrace, has been waiting for those arcs since the match began. It takes her four seconds to read them backwards to the ridge. The second salvo does not come.
There is a link in the chain I could not reach. Their relay was behind the battery, and I said so at the briefing, and the company conceded it, and it did not matter, because a chain with five links held against six is still a chain the Covenant could not walk through. Their exploit column comes down the risers at twenty minutes into a station that is intact and knows it is coming, reaches the flat, and turns.
I log the turn. Then I log the time, because the Concord believes the right timetable prevents most wars, and I have just watched one prevented, and somebody at Meridian will want the minute.