S-5 is sort of a catch all: Civil Military Affairs.
(And yes, for the hyper-astute, Big Green has mucked around with everything above -4 recently. DILLIGAF? It hasn't changed for the Marines, and the function is what's important, not the newest numbers in this year's Doctrinal Flavor Of the Month.)
Part of it is used in peacetime to catch the Morale, Welfare, and Recreation aspects for friendly forces. As such, it encompasses the Chaplain, and usually at least one junior SLJO: the Shitty Little Jobs Officer, which is usually one of a number of brand new 2nd Lts. in a unit, who get handed the crappy box-checking functions no one with more serious slots has time for: voter registration, dependent housing, Equal Opportunity, Sexual Harassment, and a dozen other touchy-feely PC bullshit things that have nothing to do with military operations, but everything to do with taking care of military personnel and their dependents, and/or making the higher up panjandrums and their civilian overlords happy. Some of them really matter, and some of them are tits on a bull.
On deployments, it also encompasses everything that a given organization does that impacts the civilian population, and everything the civilians do that impacts the group's mission and operations.
In times past (say up to 1965 or so) military units did what they did, and largely regarded the civilian population as just another obstacle, or at best, a neutral entity.
But as insurgency and counterinsurgency became important, and even more so for an unofficial group in whatever scenario you envision, the S-5 functions are half the battle.
Half. The. Battle.
Below is the official breakdown, with all the jargon buzzword bingo letters explained.
Rather than try to cover this in shorthand, this is one section where you should see the entire breakdown from the horse's mouth, to see what all is involved.
Staff Responsibilities. S-5 responsibilities include:
- Advising the commander on the effect of civilian populations on military operations.
- Minimizing civilian interference with operations. This includes dislocated civilian operations, curfews, and movement restrictions.
- Advising the commander on legal and moral obligations incurred from the long- and short-term effects (economic, environmental, and health) of military operations on civilian populations.
- Advising the commander on employing military units that can perform CMO (Civil Military Operations) missions.
- Operating a civil-military operations center to maintain liaison with other US governmental agencies, HN (Host Nation) civil and military authorities, and nongovernmental and international organizations in the AO (Area of Operations).
- Coordinating with the Fire Support Coordination on protected targets.
- Planning community relations programs to gain and maintain public understanding and goodwill, and to support military operations.
- Coordinating with the SJA (Staff Judge Advocate - military lawyers) about advice to the commander on rules of engagement (ROE) when dealing with civilians in the AO.
- Providing the S-2 information gained from civilians in the AO.
- Coordinating with the PSYOP (Psychological Operations) officer on trends in public opinion.
- Coordinating with the surgeon on the military use of civilian medical facilities, materials, and supplies.
- Coordinating with the PAO (Public Affairs Officer), and PSYOP officer to ensure disseminated information is not contradictory.
- Helping the S-1 coordinate for local labor resources.
- Coordinating with the PAO on supervising public information media under civil control.
- Providing instruction to units, officials (friendly, HN civil, or HN military), and the population on identifying, planning, and implementing programs to support civilian populations and strengthen HN internal defense and development.
- Providing technical advice and assistance in reorienting enemy defectors, EPWs (Enemy Prisoners of War), civilian internees, and detainees.
- Participating in targeting meetings.
- Coordinating with the PM (Provost Marshall - the head military cop overall in a given unit) to control civilian traffic in the AO.
- Helping the S-4 coordinate facilities, supplies, and other materiel resources available from the civil sector to support operations.
- Coordinating with the S-1 and SJA in establishing off-limits areas and establishments.
- Coordinating civilian (legal) claims against the command/higher authority with the SJA.
Staff Planning and Supervision.
The S-5 performs staff planning for and exercises staff supervision over:
- Attached civil affairs units.
- Military support to civil defense and civic action projects.
- Protection of culturally significant sites.
- Humanitarian civil assistance and disaster relief.
- Noncombatant evacuation operations (NEO).
- Emergency food, shelter, clothing, and fuel for local civilians.
- Public order and safety as they apply to operations.
If you're thinking of a neighborhood protection team, these considerations apply.
If you're thinking of an underground resistance movement, these considerations apply.
If you're thinking of an insurgent military organization, these considerations apply.
If you're thinking of an eventual fully functional military structure, these considerations apply.
The total number of instances where these considerations don't apply (except perhaps for a family staying entirely self-contained on its own land, forever, without any outside interactions; and maybe not even then) is NONE.
Re-read that point, please.
Whether we're talking patriots in North America circa the 1770s, French Maquis in occupied territory in the 1940s, a VC guerrilla in the jungle, Al Queda or ISIS in the desert, or you and your tribe when the Zompocalypse hits, Mao got this right:
"The guerrilla (insurgent/patriot/liberator/whatever) is a fish that swims in the sea of the people."
They will feed you, join you, hide you, spy for you, cover for you, cheer for you -- OR NOT.
On an individual basis, "NOT" looks like Che in Bolivia.
If you want to have your head blown off, and get on a t-shirt posthumously, ignore the S-5/Civil Military Affairs considerations, and don't plan for them.
As one egregious example, some monstrously huge dumbfuck suggested in a comment stream sabotaging the inbound rail lines to a notional major city, as Some Great Idea.
Okay. Now the trains won't roll there. Well played.
So you've just insured that the people that grow or make the goods that formerly travelled there will be broke. They're now on the side of the people you were trying to harm. Strike One.
They may have been willing to supply you with food before, but now that they're broke, they've left the area. That's now a Two-fer.
Everybody who gets killed or injured will have family and friends; they're all now on the other side too. You're at a Hat Trick.
And the people at the end of the line, the ones you thought you could starve? Guess what: they don't just lay there and die off conveniently. They're coming looking for you, with a passion, because you took the food out of their kids' bellies. They'll hunt you down with a purpose, and stake you out across the rails when they find you, and wait for the next train to come by and see you to your reward. Congratulations on achieving the Grand Slam of Fail.
The same considerations apply with dumbassery like cutting power to an entire city, etc.
Instead of coming up with hare-brained (look it up sometime, and see how small a rabbit brain is, m'kay?) ideas like that, run them through the S-5 filter. You don't want to destroy the train tracks for everyone. But taking out a train loaded with the other side's troops would be splendid. Patricularly if you made sure to let bystanders know ahead of time that "you might want to take the next train".
And you don't want to dump the entire power grid. But taking out the transformers upstream from a HQ or internet data mining coordination center would be your own version of a smart bomb. Go with those, instead of being a not-so-smart bomb.
Seriously, real life here: how do you think average people stuck in traffic regarded the @$$holes in the Occupy! movement, when those fucktards blocked traffic headed home at rush hour? All they accomplished was thousands of people begging the cops to wade in and start cracking heads. Learn the lesson: childish, nihilistic orgies of Stupid will get you the same crowd of well-wishers hoping somebody gives you a PR-24 shampoo, or worse. And when they get the chance, they'll dime you out to the authorities, and the extra bag of goodies they get as a reward will just be a bonus for them.
It doesn't matter if you're the army of the World's Last Superpower, or you're just a small band of merry men with a purpose.
Vietnam, Afghanistan, or Malheur.
When the population is on your side, you might win, and you can't lose.
When they aren't, you can't win, and you'll probably lose.
Long before then, you personally will probably be dead. Or in prison.
Or learning to breathe between trips underwater, until the people who caught you have everything in your head. Think about all those craptastic terrorism provisions and all the ways domestic authorities can find to send you to Club Gitmo, without any mention of due process once they invoke the magic "T" word. So, maybe you want to leverage some odds in your favor just a wee bit.
Let a well-run S-5 section keep you from screwing yourself, and see if you can win some hearts and minds. At any rate, enough of them to keep you in business.
Any group needs someone to think about the secondary consequences, and the tertiary consequences, and the consequences to those consequences, to everything that is done, for all the various bystanders - both close, and far away just watching vicariously. And to avoid collateral damage, to those you'd like to persuade, or at least persuade not to hate your guts, and whenever possible, to minimize and mitigate damage and injury to them. Just like you'd want done if it was your family affected, right?
Watch the café scene near the end of The Great Escape:
(James Coburn has successfully bicycled across Germany and France, and finds himself sitting at a table at an outdoor café. Some German officers are sitting nearby. The café phone rings, the waiter answers, and comes over to Coburn, and tells him the phone call is for him. Surprised, he plays along, they all go back to the bar, and they all duck behind the bar just as a car full of Resistance guys zips up and hoses the Nazis down with a machinegun, then speeds away.)
Sweeeeeet! So...who made the phone call?
The 1944 version of Maquis S-5, of course. That is how you want to roll, right? Right.
Otherwise, you're just another g--d--ned bomb-throwing anarchist, and nobody mourns them when they end up strung up from the nearest tall object, or get thrown in a hole so deep they pump air and light into it from out here in the free world.
So as usual, Don't Be That Guy.