All the modus operandi came from the TRS--the Titan Readiness System. It provided a detailed list of procedures to follow during assignments. Most likely events, from encountering a purple to a horde of whites boarding them, had some mention.

  Re-5 didn't think the thoroughness was a bad choice, but there was plenty of clutter the TRS didn't need. A few too many paranoid men and women had had the chance to add on their own "necessary editions."

  When the Nyx Breaker's assignment began, they were on modus operandi brown. They hadn't encountered Aud until the fort, so that was fine, even if they were operating without a friendly Titan.

  Like all things good, that didn't last. Skirmishing with the Aud in the western greater tunnels was just the start. The difficulty involved with avoiding larger hordes and blitzing their way through smaller ones kept going up. They'd almost jumped to the opposite end of the spectrum by now.

  They'd stayed in modus operandi blue the longest. The Titan she ordered about was in an active combat zone with a heavy presence of Aud. All military crew members, even reserves, had an obligation to report for duty. Non-essential activities had ceased, and localized anti-grav fields buckled down loose cargo.

  So what did modus operandi purple mean?

  Short of mass casualties, purple in the TRS was as dire as conditions would get. Like purple Aud themselves. It was for Titans embroiled in active combat zones expected to face a horde or at least one purple. Both were worst-case scenarios as far as the First Ray was concerned. Good sitesmen strived to avoid either, no matter the circumstances.

  In that sense, she was already a terrible replacement for Ze-4, wasn't she?

  She imagined the controlled panic running through the servicemen. Even without notice, pilots would run to the front-facing garage as fast as their legs would go. Suiting up would become their life's purpose in an instant.

  Previously, it could've been something mundane, like a break in the mess hall. Or waiting for orders on a bunk. Anticipating the inevitable, and dreading it at the same time.

  Techs transferred data and brought around status updates. The command compartment filled with chirps and dings flitting across the console screens. At least one went off per second.

  Inventory management would've doubled back to the stores to strap everything down. They did it physically with belts and braided cables. Continuing to rely upon the anti-grav generators would've turned against them eventually. Natural gravity and the anti-grav fields struggled for domination inside the Titan.

  While the generators would win out in the short term, it wasn't smart to spit in the face of physics too often. The Titan's structural integrity would suffer from the confrontation between attraction and repulsion.

  She rubbed her eyes. How many hours had it been? Over half a day now. Her circadian rhythm was catching up already? It was too early to start herself on stimulants if she wanted to stay in sync with the rest of the crew. She held her breath. Short thirty-second cycles could kick up her natural adrenaline in the short term.

  The Nyx Breaker's pilots guided it down its path, making course corrections every so often. Darkness and stone surrounded them. It lasted long enough to notice, and then they broke through the next barrier. Beyond it was another vast, open space.

  "The eye lights will help the echo room, right? Turn their luminosity as high as they can. Aside from that, I want the echo room to get a quick survey of our tunnel before doing what they need to."

  The noise from burrowing through the rock and stone had all but exposed them. Aud would already be on their way. By further broadcasting their location, she'd only speed the process a little. They needed every advantage they could get, and locating targets as soon as possible was one of them.

  "The echo room is on it. Should we post WAVs outside?"

  "No. We'll condemn our pilots to death for no purpose." It would be a risk, sure, but it could pay off. If they spread out a net of targets around the Titan, oncoming Aud would take more time to reach them.

  The Nyx Breaker would always have the most value, no matter which way she tried to interpret it. Doing so wouldn't even be outrageous, following the First's precedent.

  Abandoned, used as bait, and sacrificed for "the greater good." Many times, servicemen had gone through this treatment. The war had a three-century-long storied history, after all.

  Once, Titans were disposable assets, too. This was different from that, though. Pilots were the most likely to engage the Aud up close. They had the highest casualty counts because of the activities they had to do. Pilots knew their place in combat.

  Assuming she was willing to send out a couple of squads, they only had so many WAVs to spare. Scutumsteel, while not hard to produce, had high material requirements. All the other electrical and mechanical components that went in had their own costs.

  Then there were the human costs to consider. Engineers and techs could replace dedicated pilots in an emergency. All military training included coverage on maneuverability and combat within the suits.

  If she could act like a machine and condemn those servicemen to die, she'd still be tossing away so many WAVs. They couldn't recover them without risking more casualties or Aud breaching the Titan. Her wrists knocked against the edges of her cybernetic implants on either side of her head while massaging her temples.

  Expending them now would be trading strength. When she could so obviously see they'd need every fighting advantage for when it came time to extract any survivors, it made no sense. Not if. She wouldn't let it become if. They'd find someone and bring them home alive.

  The pilots controlled the Nyx Breaker's coiling action. The links, each a couple of compartments' worth, formed around each other. What cohesive shape it'd had before vanished beneath a spiraling, undulating mass.

  They were still moving, creeping toward the center of the tunnel. The head peeked out from the tip of the new shape, bringing its beaming lights around like a watchtower. Darkness retreated and formed back up around the light's path.

  Thousands of the tiny legs reemerged while the knees flexed. From the protruding secondary limbs, short-barreled sonic emplacements extended. Over those, like bayonets, came thousands more melee affixtures. At the slightest movement, bristling cluttered the Titan's audio sensors.

  The echo room provided their preliminary scans shortly. What she studied all but demanded she wince. Like payment, for forcing herself to look at something that promised such inconvenience.

  Their tunnel extended both ways until connecting with other greater tunnels. The north direction continued for kilometers, and the south one went even longer. Both had sharp twists and turns, misaligning them from a steady, solid path to chart.

  At least the ground level stayed uniform except in abnormal areas. Uninterrupted lines of sight from both directions? They'd have the chance to strike first in every potential skirmish.

  Instead of feeling eased, she shifted her weight. The southern stretch of their tunnel connected to a vertical shaft. Few of the greater tunnels were vertical instead of horizontal. When the map updated to include the positions of nearby hordes, she got a double-gut punch.

  She traced over the mental image with her fingertips. Would it look strange if someone saw her doing that without seeing her implants first? Qa-3 wouldn't give this a second look, would he?

  A horde from the north. Smaller movement clusters from the south. That direction should've been too stressful to lock down. She rolled her eyes. It would've been the case if not for the vertical tunnel.

  The map updated every few seconds. Between, pauses, showing an immeasurable amount of movement, rushed down the shaft, like a flood. Big enough that they couldn't get an estimated number? Maybe it was two that'd merged on their way from wherever in the tunnels they'd come from.

  The vertical shaft merging with the ceiling of their tunnel was too close. Once the Aud began falling through, they would be on top of them. To Aud, a handful of kilometers counted as nothing.

  "Can we move north for more distance?"

  "We could. We shouldn't." Instead of hearing his voice in her ear, it came from behind her. She spun as he pulled himself over the rail. He reached out a hand, and she stared at it.

  He cleared his throat. The noise did the trick, and she crossed over to take it and haul him the rest of the way up. He knelt by the edge to restrap his boots. Her stomach made an ugly shift as he looked up into her eyes.

  "The echo room has already started intensive scanning. Should the Nyx Breaker shift even a dozen meters, the progress will reset."

  "Tell them they better work fast, or I'm tossing one of them out to the Aud."

  The ghost of a pale smile graced the officer's lips. "Sir. They're here."

  The superhorde would reach them first. Priority targeting went to it. Emplacements shifted their aim, saturating with energy as the targeting programs waited. Focusing down as many Aud in the air as possible would be their best bet on survival.

  Though there was more to the situation than that. The Titan had to contend with a pincer assault from two transversal directions. To complicate things, they also needed to divide their defensive options across many movement planes. All combat became frustrating once you had to consider vertical aiming as well.

  The falling horde would get focused down first. Doing that would only give them an advantage depending on their volley's effectiveness. Aud were heavier than WAVs and would have higher terminal velocities. They'd hit the ground so much sooner than she'd like.

  Once enough had survived the trip to the ground, they'd divert firepower down there. Two-thirds seemed appropriate. Cylinders would stay in reserve, and the targeting programs would use them against the ground Aud. The explosives and other munitions options were too heavy for distant, fast-falling targets.

  She scarcely blinked while watching the screens out of fear of missing the moment. The movement detected was almost at the bottom of the shaft.

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  Below, techs called out numbers to each other. The Titan's close-range scanners and optics were adding their data to the picture. From what little she understood from the disjointed snippets, the Aud were falling faster than predicted.

  She grimaced, tucking her hands behind her back. Fingers interlocked with each other and tried to strangle the thumbs. "Are the electrics primed?"

  "Always have been, sir."

  "Then what are we waiting for, Qa-3?"

  Sonics, electrics, cylinders, and netting made up the military's main weapon categories. They couldn't make much use of netting, unfortunately. A Titan, unless designed to be a stationary fortress--those hadn't lasted compared to the ones that could move worth a damn--was too mobile. Netting cannons needed a steady platform to track targets from.

  That said, the other three were still potent tools to use in the conflict. Cylinders were simple in function, concept, and design. They exploded. Some tossed up an obscuring smokescreen. Some delivered large payloads in a small detonation chamber. Others still had more exotic effects.

  Sonics used physical ammunition that varied in size and range. Their firing mechanisms stopped them from being mundane firearms.

  Sonic emitters built into the guns launched a concentrated burst of amplified sound when triggered. That kicked the round forward, increasing velocity even more. So far, humanity hadn't yet come up with a more powerful version of the slug-thrower.

  And the last category, electrics. Unlike the other two, this category needed nothing to function aside from a power source. Energy was the input, energy powered the process, and energy was the output.

  Discharges ran through a focusing crystal, producing beams that were as easy to aim as laser pointers. Upon impact, heat and residual electrostatics would burn and char.

  Cylinders were too slow to hit targets at that distance and speed. Sonics suffered the same problem while the skirmish was just beginning. But electrics were energy ripping through solid matter. They were exempt from many restrictions, chiefly gravity.

  Which made them the perfect emplacements for the opening salvo. The tunnel lit up as beams of crackling light ripped themselves airborne. The first targets were too far away to hear, but the gunnery crews looked like they had no trouble imagining the roars of pain. Of rage.

  That second one would be especially good for them. Rage made Aud frantic and careless, in their version of it. Not all that different from how she'd handle a human opponent. Unbalance and destabilize, and keep them confused and at a distance for as long as possible.

  Hundreds of these beams launched from the Titan's ropey body. Their targeting programs rewarded them shortly with small victories. From this far away, they couldn't tell well whether an Aud was dead. The policy she'd settled on was that once a target looked like a charred comet, an emplacement should find a new one.

  The sheer volume of electrics was dizzying. The number of emplacements they carried felt gratifying, but the horde hadn't begun to flow from the shaft.

  As things stood now, these were the first Aud lucky enough to fall faster than the rest. Enough would soon fall that they wouldn't see the shaft itself. When there was more, their bodies would create the illusion of a flood exploding free.

  There would be too many to afford to be picky with targets. They could manage that right now, and she wanted the Titan to take advantage of that. Even if a killed target had white fur, it would still be one less to confront later.

  The electrics pinpointed and focused on the lower tiers. White, orange, and yellow. Doing so spoiled them for choice again, since those were the most common colors.

  "How soon until the fastest descending targets enter sonic range?"

  "They're already inside it." Qa-3 raised his hands in a placating gesture. "But their predicted accuracy isn't high. I recommend we keep them in reserve until the targets are close. We only have so much ammunition to spare. Our targeting programs need to guarantee hit rates greater than seventy-five percent."

  "Lower it to sixty-five, and you've got a deal. We can't afford to wait that long." Survival hinged on knocking as many Aud out of the air as early as possible. Progress would be harder to make once the northern horde came into view.

  The electrics might pack a punch at a distance, but successful hits delivered no kinetic force. No matter how much an Aud got hit, its trajectory wouldn't change.

  The sonics, though, could bruise and break at the same time as they knocked the Aud off-course. If the Aud sonics fired at were on the ground, that'd be a challenge. But a free-falling target had nothing to brace itself against. "How do the electrics compare?"

  "The initial salvo had a ninety percent hit rate. The earliest targets have entered a range where any electric beam is all but guaranteed to land."

  "Good. Divert more generators. I don't want us to have to be frugal with the electrics. Unless they're at their heat limits, I want them firing at a staccato pace."

  Whether she could authorize overusing the emplacements was open to interpretation. She'd knowingly cause preventable structural damage, and they might need the firepower later. Ze-4 had repelled one blue already, but there were purples in here with them, too. She huffed and decided no.

  'The Fifth especially would find some issue with that. I'd bet another year of compulsory service on it.'

  "On it."

  The electrics' firing rate increased while she collected diagnostic data. Hundreds of beams per second increased to nearly a thousand. More targets turned into unrecognizable, blackened corpses faster. Not fast enough, but she couldn't feel too greedy about it. Faster was faster.

  Another salvo ripped into the falling targets. The deadly light show was a sight to behold, as much for the servicemen as Re-5 imagined it to be for the Aud. Would her reaction differ if she were one of them?

  Aud were impervious to impressive amounts of firepower. Even fatally injured, they still hounded their prey with a single-minded fixation. Everyone, scientists and soldiers both, agreed it was too powerful to be natural.

  Natural in the conventional sense, not the looser standard that applied to the Aud. Was it disregard for their safety? The Aud stayed in their tunnel-visioned mode, even when others above and below turned into smoking caricatures.

  The other hordes were still closing in while they shot up the shaft entrance. The south's movement clusters would come second. They had to climb a near-vertical tunnel before they came into sight. If the Nyx Breaker were closer to that side, they could've launched cylinders down it.

  The horde coming from the north would get to them faster than that. Their electrics already had visual confirmation, and they would soon enter firing range. Diverting emplacements away from the superhorde would become necessary to slow them down.

  Knocking down their numbers in advance was the only way to stack the odds in their favor. That wasn't to say nobody felt disgruntled over abandoning all the easy, free-falling targets.

  This wasn't anything particular to fuss over. They fought a foe they couldn't trap, outrun, or avoid without difficulty. Humans couldn't kill the Aud without dedicated resources or sacrifices. All their match-ups would stay unfavorable from start to end.

  The Aud approach came almost in waves. That should've been cause for thanks, since they could focus on faster-arriving targets. If they all came as one superhorde, there'd be fewer tactics involved. At the same time, how was it fair that this was what passed as good fortune? The familiar flare of indignation felt like it made her blood boil.

  As she'd predicted, more Aud fell from the shaft. Enough came out per second that it did get obscured. The Titan's autonomous intelligences had the thought processes of workaholics. Their work showed that through and through.

  Targeting programs got directed at different clusters of movement to mark. Special cases that the autonomous intelligences thought were marker-worthy got singled out.

  Others left out of the identification and targeting loop helped position the emplacements. The markers helped differentiate which groups of Aud amongst the visible hordes needed culling.

  She watched her people inside the command compartment. Her heartbeat slowed when she noted the tense atmosphere had receded. The servicemen--her servicemen, now--had strong training and loyalty that they devoted to each other. Not even an unfamiliar scenario that all but promised a brutal end could challenge that.

  They all had thoughts of cowardice. Pointless thoughts. She knew because she did too. Re-5 wanted to be brave. To be a serviceman her parents could be proud of. Someone she could feel happy to be. Being a coward wouldn't allow her to be that person.

  But being a coward would keep her breathing, so she could still be a person at all. A person only had one life. Shouldn't they cherish and work to preserve it above all else? Why else were they born, if not to live?

  The ventilation above her drafted fresh air into the command compartment. Goosebumps popped up when the new cold touched her. The number of targets marked on the screens was still increasing, no matter the kill count.

  The one thing keeping the servicemen in line was knowing that if they could do their part, it was enough. If they could do their assignments, it would let others do theirs.

  They couldn't force the others to assist in the war effort, but at least they wouldn't hinder others. At least they wouldn't be cowards themselves. It was what many of them hoped would see them through this assignment and return home safe.

  This knowledge--this truth--let them continue their tasks. They looked indifferent.

  "Our sonics, sir? The earliest targets are in range."

  "Don't wait on my account. Are the accuracy parameters still below seventy?"

  "They reached sixty-four not too long ago. They'll need six seconds to reach seventy."

  "It's acceptable." Strictly speaking, a single percentage point wasn't worth much. But the larger the quantity, the larger the impact a single percent has. Dozens of shots would miss when Aud flailed their bodies in impossible-to-predict ways. Or, rarer, the targeting programs would make errors.

  "I'll inform the gunnery crew."

  While he did that, she'd continue overlooking the entire situation. Ze-4 had told her commanding a Titan was like playing a game. That hadn't made sense at the time. As his assistant, she'd handled logistics from head to tail. Issues on everything from the generators' output to how inventory stored rationed goods had popped up.

  But she'd walked more than a few meters in his boots since then. On this side of the work, she shouldn't have to concern herself with those things. That was why she'd been there, why the sitesman all had assistant officers. There was too much to handle at the sitesman's level.

  As aide, she'd needed to control the generators' output for the emplacements. As acting sitesman, Re-5 would have to expand the scope of that concern to the rest of the Titan. Five different tasks occupied her at any given moment, while another five waited at her peripheral consciousness.

  It was all the more amazing that Ze-4 had performed his role while making it look effortless. He didn't have cybernetics. Was the difference between her and a better sitesman simple experience? She knew regulations and logistics like the back of her hand.

  But this was a first, being thrust into a position of leadership. Uncomfortable, tenuous leadership. Some of the techs below had glanced up at her. Not too long ago, those nerve-wracking looks would've gone to Ze-4.

  She accepted a handheld screen from a courier and signed off on a transfer of munitions. Qa-3 took another one while she was still skimming through. Better to take up another task than waste time considering herself. If she had time for that, she wasn't being productive enough.

  The echo room wanted more generators diverting their output to their compartment. When asked for a status update, an Ancient on the other end of the call chided her and told her to stay patient.

  The feeling of chagrin hit her like a sour odor. Its familiarity would've spiked her annoyance if she weren't expecting it to. That she was doubled it. The last person who'd scolded her was one of her instructors at the Light Institute. Around the same age, if she guessed right.

  Ze-4 would've invoked his authority to chew the other Ancient out. She instead closed the call and decided a better use of time was to help Qa-3 with the still-growing backlog of logistical issues.

  He'd rescued her from the bulk of them, and now she took some off his plate as silent thanks. They'd agreed he'd intercept smaller considerations that wouldn't need knowing the whole picture. Still, it was a lot for a single person to handle.

  When the sonics fired their first salvo, she looked back at the overhead screens. Hundreds of scutumsteel rounds spun through the air to join the electric beams. Those at the head of the metal cloud arced and connected with their targets.

  Satisfying. It was so satisfying to watch a solid and thick slug punch an Aud. If her fist could do anything, she'd've taken its place. Her HUD showed her summary statistics of the salvo, and while--

  Her eyes doubled back. What miracle had the gunnery crew stumbled upon for this? Directly contradicting the predictions, almost eighty percent of the salvo had struck true. Her fists clenched behind her back.

  Even targets only hit once went tumbling back. Their new trajectories ensured they would land further from the Nyx Breaker. If most of the superhorde got a scutumsteel round in the ribs, the Nyx Breaker would regain twice the starting distance!