I posted this in a different thread, but there is an actual discussion going on here, so I figured I'd post it here as well, sorry if this is not permitted.
As we all know, Hitler was never assassinated, and the closest attempt was the July Plot, which failed miserably. Even the allies never got to him, no one really did-- ultimately he died by his own hand; he lived as he died, paranoid and dishevelled. When looking at this question, it would be best to know how the plotters actually intended to execute this plan of a coup. Without the details, it is hard, but we can speculate. However, there are a lot of factors to take into account. As I continue, I would like to say this is operating under the assumption that the putsch or coup is attempted in Berlin while Hitler is in the Reichs Chancellery (as it is my belief this is their best, albeit not a good one at that).
First, we should look at the state security apparatus of the Third Reich, specifically in regards to the protection of Hitler’s person, as well as the presumed location of the Putsch, the Reichs Chancellery in Berlin. In Berlin itself, there are two large formations we should be looking at: Leibstandarte Adolf Hitler, and the Wachregiment Berlin (though it should be noted that the former was actually involved in the occupation of the Sudetenland, it is likely the Wache Reichskanzlei battalion remained in Berlin). Furthermore, we have the various formations responsible for Hitler’s close protection detail, being the FBK (Fuhrer Escort Command) which consisted of an eight-man team each armed with two pistols and several magazines. There was also the Reich Security Service (RSD) which were in effect SS men acting in the function of security officers or military police, which would have certainly had a presence in Berlin within the government quarter. Asides from these, there would also be the regular uniformed police, which would at this time also be under party control, as well as any armed SS, Wehrmacht officers, or even Government functionaries present (which could potentially be Party loyalists).
So now, how do the plotters actually go about killing Hitler (which they have to, or else game over, as witnessed with the July plot). Simply getting to the Reichs Chancellery is going to be difficult, as with the security presence there (especially at a time of heightened tensions such as the Munich Conference) you are going to need quite a few men. This is because not only must the forcibly storm the building (as they certainly aren’t going to allow an armed group of men inside, especially in the Fuhrer’s presence.) but they must also fully surround it, to ensure Hitler doesn’t escape and the building itself is fairly large. This must be done because the second gunfire erupts, whatever protocols his close protection detail has in place will go into effect, not unlike the modern secret service, we have to remember that for all the convolution, nepotism, and other inadequacies of the Nazi state, there was still some degree of professionalism. We have to remember that this guy was rolling around in a Mercedes-Benz with 18 mm armoured plate and 40 mm ballistic glass. These protocols could mean a matter of things, whether it be moving Hitler to a secure location on site such as the Vorbunker (which itself had a permanent guard detail and was heavily fortified as one can imagine) or evacuating him completely via motorcade, as he would surely have vehicles nearby.
So, perhaps a bit more than a platoon might be necessary? Especially if Hitler and his entourage manage to fight their way out or slip through a side entrance, but the only way to prevent this would be to set up control points on the roads surrounding the chancellery. Unfortunately, the more troops the plotters use, the far more likely this is picked up by one of the numerous state security agencies. It is not an easy task to mask or otherwise legitimately explain the movement of troops, especially if you try to use something like a company (which I wholeheartedly believe you would need in this instance). This is where the conundrum lies, how many troops do you use? Use too few, and risk being repulsed or Hitler escaping; use too many, and you risk being caught before you may even reach the Chancellery. Not only this, but the question stands: where do you get these troops? Your plotters are too few in number, and for the most part, not in any meaningfully useful position-- with the exception really being Halder. Presumably the plotters managed to find some naive junior officer OTL, but in the culture created and cultivated by the Nazi regime, those who don’t actively curry favour with the leadership or those in positions of power, tend to lack in the political capital necessary to mobilise the sufficient resources to pull a putsch such as this off. Compounding this, there would also be those enterprising individuals who would happily (if afforded the opportunity) expose this plot, as loyalty is rewarded. All it would take is a logistics clerk reporting unregistered withdrawal of arms or munitions from an armoury, or a sentry witnessing the departure of several truckloads of infantry (without any known issuing of orders authorising such a troop movement).
If by some miracle the plotters manage to reach the Chancellery without raising any red flags, the moment gunfire erupts (which I wager is just as they begin to approach the sentries), within x amount of minutes you are going to have Hitler either being secured away or evacuated, as well as a telephone call being made or wire sent to the nearest garrison as well as other state security agencies. How long it takes these additional loyalist forces to reach the Chancellory is anyone’s best guess, however is this timeframe feasible to fulfill the task at hand? With the Fuhrer’s life at risk, you are going to have a swarm agencies and units rushing to save him, not only out of a sense of ideology or loyalty to the party, but also fear. If Hitler survives or dies yet the Party remains in power, those who failed to respond immediately, effectively, and ruthlessly to the putsch are at risk themselves of being charged with failing to secure the safety of the Fuhrer. Then the question arises once more: bring more men and try to establish a perimeter to block or delay any relief force, or is the risk too great?
Then, consider the optics in the grand scheme of things, especially in the national political discourse in Germany (or what remained permissible). In 1938, you aren’t trying to kill the man who started the second world war or ordering the perpetration of war crimes. You are trying to kill the man who had brought stability after years of political instability and parliamentary turmoil, a man who has created a positive economic outlook and brought down unemployment numbers. This is the man who has seized control of the state through effectively legitimate means, who vocalised what can be described as the collective conscience of the German people (I think this can be attributed to Dr. Jordan Peterson though I don’t recall). Of course the plotters can present their case, that the risk of war is too great, and this crisis must be averted even if it means taking an unlawful action against the government. In my opinion however, this would fall on deaf ears, as I personally believe the general public-- particularly convinced National-Socialists, would simply perceive this as opportunists gunning down their Fuhrer, the man who could have perhaps led Germany to prosperity and out of the shame brought upon them by Versailles. These men would be labelled as traitors, mere copycats of those same designing Jewish bankers and weak-spined politicians who had perpetrated the stab in the back over a decade prior, all in one of the Fuhrer’s most crucial moments, negotiating the repatriation of ethnically German lands back into a unified Reich. After all, Hitler had achieved the return of Saar, remilitarised the Rhineland uncontested, and fulfilled his vision of Anschluss with Austria, who is to say this was beyond his grasp?
Having said all of this, I must say that it is my firm belief that any such adventure or folly as attempting to overthrow Hitler at this stage would be extremely difficult, and is likely the reason why it was not attempted in the first place. Sure, Hitler got his concessions at Munich so this planned putsch attempt was aborted, but I think really the plotters were still uncertain or hesitant themselves. To commit to something such as this requires extreme dedication, as if you are unwilling to risk your life, you are unlikely to commit to it fully. Simply look at how long many of these same plotters waited before finally attempting the July putsch. Sure, there were other attempts, but no one (to my knowledge) prior to that July was willing to see this great undertaking through to the very end, regardless of the outcome. This is not to say these men lacked fortitude, but more so that they themselves wished to benefit in the post-Hitler era, whether it be assuming roles in the general staff or the government. These were ambitious men, make no mistake about it.