I'm wondering how much information an Imperial Guardsman is going to be let in on. Is he going to know the whole plan, a small fraction, or nothing at all? This came up after I was debating whether the PCs should be invited to an orders meeting, since while they're all ranked as Riflemen one of them is the platoon's Ratling scout specialist, and would thus probably be invited. Is this correct to the Guard's chain of command, or would they be told to sit down and shut up?

For that matter, how much should the PCs be allowed to form their own plans or have to follow their officers?

Depends on the regiment. For a general average, I'd say 'No'. Guardsmen of the lowest rankings are going to be metted out their orders, and expected to carry them out to the letter. It's up to their CO's to attend such meetings, and any significant information (As s/he sees fit) will be given as necessary.

Knowledge is dangerous, and ignorance is a blessing; these feelings carry over into most aspects of 40k life in the Imperium. I imagine most IG, between the threat of their cowardice, and the likelihood of their prompt death, need to know as little as possible, lest they give up intelligence. In a few instances, I've actually considered making Vid-Relays common kit, and vox boxes can allow, under some circumstances, for orders to be fed in as needed. Otherwise, I could see the Sergeant having info, and being told not to wave it around too much, and maybe a character whose specialty is critical, such as demolitions, or something. If the party has a Commander ASpec, I'd probably, in my own cases, give them more intel, as they are "higher-ranking officers" in my eyes.

Seems fair. On the other hand though, I could always alter the fluff to give them more independence than normal - as Highborn Light Infantry, with a Phlegmatic Colonel, I reckon they'd have a fair amount of tactical freedom and would probably be let in on most details of the plan (they're based on the 95th Rifles - in spaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaace ).

Although, the Squad doesn't have anyone of rank so giving orders would be quite difficult. The problem is that in the one combat we've had so far they insisted on using their strategy, not the lieutenant's.

Or maybe I'm just too nice a GM...

Could see that; I'll fall back to hide behind the "depends on the regiment" defense. As your troopers level up, and possibly get promoted, but if they can still find a way to be the footsloggers, rather than leading hordes around by the nose, they'd certainly get more and more intel.

That depends on regiment obviously, as there are many different cultures within the guards.

Armies operate with a strict hierarchy to increase efficiency. For example, a division commander would meet with his immediate subordinates (brigade commanders and divisional assets commanders such as engineers, artillery, logistics, intelligence etc.) and pass on/discuss his orders to them.

The brigade commanders would then meet with their regimental commanders and brigade asset commanders.

The regimental commanders would then meet with their battalion commanders and regimental asset commanders.

A battalion commander would then meet with their company commanders and battalion asset commanders.

A company commander would meet with his platoon leaders and senior nco’s.

And then the platoon commander would meet with his squad commanders to tell them the plan and any pertinent information.

The squad commander will finally be the one to tell his squad (i.e. the average grunt) what the mission is and what they need to know (goal, opposition, route, friendly assets, neighbouring forces etc.) And then only what really needs to be known so the enemy can’t get too much intel if a grunt is captured and interrogated.

This would be the normal template. For special missions or special troops, more information would likely be provided to increase efficiency and the likelihood of success. But an average squad will have only the most basic information.

Which is where ‘rumour central’ comes in as the soldiers gossip like old crones. The general/colonel/lieutenant’s orderly will be plied with liquor for inside information while the old hands will make predictions based on earlier experience……

As to your next question, an experienced squad commander will know how to utilise his men to their best advantage commensurate with the platoon plan or company plan. Obviously, squads can’t go around on their own or they’d block firing zones, maybe run into friendly fire, hold up other troops etc.

However, this is a role playing game. Not a simulation. So you should decide how grimdark you want your players to feel. Maybe they don’t even know the name of the planet they are fighting on, or why they are fighting. Or maybe they have been given various propaganda pamflets and holo shows with various information. But make sure to give them a lot of freedom to plan their own actions or the game will be boring for them. If they just wanted to follow orders, they’d be at work and being paid .

There's a part that should be included in your general orders for a mission called "commanders intent". The idea is to illistrate the whole point of a mission or campaign and the spirt of any orders you recive so as to keep you focused towards the ultimate goal. In the U.S. military this is told to everyone, even the lowest ranking guy, however a commander needs his men to follow all orders regardless of reason and typically doesn't explain why he tells you to do something unless your part of his command. The type of commander should dictate how much the characters know though, some will want to explain every mission to the characters themselves and some will want every man to follow orders through the chain of command without question.

As military doctrine has developed, it has been discovered that the more ground troops know about the overall plan, the easier it is for them to adapt to the chaotic situation of a battlefield and make things work even when the original plan inevitably does not survive contact with the enemy. Keeping your soldiers well-informed about what they're doing and why has been discovered to be an unquestionably more effective way to fight a war. Thus, naturally, the Imperium will have absolutely nothing to do with it.

On commander's intent, give them 2 up's intent, that's 2 links up the chain of command. So if the squad leader's giving orders, give the platoon commanders intent, the platoon commander will give the company commander's intent etc. That can also be tied in as your overall objective, if the commander's intent is to take Hill X, that would be your primary objective. Alternatively, you may be protecting the flank of a force who is going to take Hill X so commander's intent is to take Hill X, but the squad's objective is to hold Street Y, to give you an idea of how intent can differ from mission objectives.

Or you could go with IG standard, do it or the guy in the cap and cloak will shoot you.