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Guidelines turned into Rules: The 3 to 1 in the Attack

On December 26th, 1776, General George Washington led 2,400 American Soldiers against 1,500 Hessian military contractors, I mean, mercenaries. In total, the Continental Army killed 98 Hessians and captured 500 more. The Battle of Trenton strengthened the position of the continental army and the influence of the continental congress, a key battle in winning the Revolutionary war.

It's a shame that no Army General would have guts or testicular fortitude to do the same today.

Last week, I described the trouble the Army has distinguishing between guidelines and rules. Take the most common guideline-turned-rule: the three-to-one advantage in the attack.

I have participated in countless training exercises, and every time the US plays the offense. And we always have three times as many troops as the enemy. Always. It's a guideline for high-intensity warfare, but now it is law. It doesn't make sense that we will always have three times as many Soldiers as our enemy, but somehow in training, we always do.

This “guideline” is so rigorously embedded in the Army's consciousness, we still use it when we plan counter-insurgency operations. Whenever my battalion conducted Company-sized operations, (or CONOPs, see the post here) during the brief our S2 always briefed the number of enemy he expected on an objective. I would listen in as the S2 briefed his portion, and as I calculated it, we had exactly three times as many troops. Either we could perfectly predict the enemy's size, or we jerryrigged our slides to meet an arbitrary guideline.

The guideline exists to create overwhelming force, and its a good organizing principle. Basically, in the attack you can have a third of your force supporting, a third as an intermediate base of fire, and the final third as an assault force. As a guideline, it works. If a unit can bring to bear the three to one advantage, they usually win.

Unfortunately, this is an example of the science of war trumping the art. The science is a chart of the relative combat power analysis of two forces. Charts with numbers are easy to understand.

What the science of numbers can’t describe, though, is enemy morale. The science has a tough time accounting for surprise. Numbers warfare doesn't do well calculating well-organized raids and ambushes. The science of relative combat power also excludes the factors of speed, mass, surprise, initiative, unity of effort, and countless other principles of warfare. I am convinced the Army would love to replace its company and field grade officers with computers; until then it will use arbitrary guidelines.

There are countless examples of Army officers surprising the enemy with fantastic results. Joshua Chamberlain's counterattack at the battle of Little Big Top is the greatest tactical decision of all time. He didn't have a three to one advantage. The Great Raid at Cabanatuan used speed, surprise and organization to overwhelm a Japanese garrison and rescue over 500 POWs. They didn't have a three to one advantage; in fact, they were at a 127-700 disadvantage (not to count the 8,000 Japanese soldiers patrolling the countryside).

And again, General Washington had more troops than his opponent, a 2,400 - 1,500 man advantage, but he attacked on a garrison in the defense. According to Army logic, he shouldn't have done so with less than 4,500 men. Surprise and audacity won the day. Current Generals should pay heed.

It is a good guideline: try to have three times as many guys as your enemy. Heck, we invaded Iraq without obeying this law, but not because the Army wanted to. Guidelines are good in their place; rules hamstring our Officers. If you are an active-duty officer, I know you have heard this rule. Please remember it isn't a law.

ten comments

A very good point to make! Especially when you see it with European eyes. It’s bloody naive to thing that numbers alone will result in overwhelming the enemy.

As for Washington… just curious, do you know his real name and his background? Might also have had something to do with the outcome of that battle…


Oh I should perhaps add: since you’re talking training exercises… are you familiar with what the Danish special forces do and how exactly they were able to win joint exercises?
That totally proves the point of this post!

And as for moral and intention – that’s all that really matters. With the right attitude, skill (training) and a realistic battle plan you can do anything!

And intention is a big one. Like f. ex. not much of an impact if people are just firing in general bursts because they in fact do have a mental problem with actually taking out the target.
Or if their reasons for signing up in the first place aren’t really what they should be. Doesn’t matter what uniform they officially wear, they will be more a liability than an bonus. Noticed, I’m nice, I didn’t use the word traitor?!


It is a factor of poor education that results in this guidelne becoming a “rule.” Without understanding the origin of “why 3 to 1”, a commander is only left to accept it as fact (it becomes dogma). 3 to 1 of what? I think its all based on very subjective look at history and what used to pass for simulation (Lanchester Equations, etc.). If soldiers and Marines learned more about the origins of this guidance and the case studies of where and how it was applied, then there could be informed judgment in application. It is interesting that you have experienced it in terms of numbers of soldiers as my experience in applying this has been to compare relative combat power, which is itself a tricky proposition. Relative Combat Power should account for fire support (air, artillery, etc.). It can also account for morale, training etc. The problem has been in the past that this last factor is very subjective. Rather than take the risk of comamnders underestimating the enemy’s ability, most doctrine tells you to gain the 3 to 1 first, then consider the morale differential as a bonus. The problem, as can be readily apparent, is that the calulation can drive caution (I won’t attack until I get 3 to 1), or overweighting some efforts at the expense of others. I could also see this whole calculus as being important under guidance that restrains external fire support. Obviously, 3 to 1 can also be looked at in many ways. One part of the art of good tactics in the past has been to shape the situation to have 3 to 1 at the critical point, even when you don’t have it overall. Semper Fi


I think it is hard to conflate hard numbers (read: man-power) with soft numbers such as morale and training.

It is like art, first you have to know the rules, then you can break them. If your enemy expects one thing, than do the opposite.


@ Eric – what good are high hard numbers when they are just not identifying a 100% with the objective? You’re much better off with fewer, but completely dedicated, troops and different tactics.

You’re right about the element of surprise.

Rules… you know I hate them, but I stick to them in order to cover my ass.
I don’t really believe in standard solutions, I much rather see what’s needed here and now and adjust to whatever the situation requires. I’m not saying you shouldn’t know rules, but it’s ignorant to just follow them blindly – just because everybody does so. On the other hand if you know them well enough, you’ll probably find another rule, which will cover you when you decide to chose a more workable, alternative solution.

@ Phil – poor education, or ignorance or cowardice?
I don’t know. But in general getting to know the origin of things or caring enough to understand what most people just swallow without ever questioning, is definitely good advice!
Liked your analysis.


It’s a good guideline and makes sense in a head to head confrontation. I agree with Phil, using tactics to engineer this scenario can’t be a bad idea while waiting until the numbers work to your favor might. Eric’s right know the rules, understand why they are rules, then use the knowledge to you benefit.


While I agree with your point in general (that there are no hard and fast rules of war, and that surprise and audacity can win the day), I don’t think your example of the Battle of Trenton would have required the 3-1 “rule” anyway. That particular ratio (technically known as the “Historical Minimimum Planning Ratio) is for attacking a prepared or fortified enemy position. As the Hessians didn’t have all of their sentries posted and were garrisoned (not fortified), this ratio wouldn’t apply in this case. Technically, Gen Washington should have used the 2.5:1 ratio of a hasty attack (you know, if he had doctrine then). But then again, these are ratios derived from historical analysis and are not hard and fast rules. As FM 5-0 states:

“Planners combine the numerical force ratio with the results of their analysis of intangibles to determine the relative combat power of friendly and enemy forces. They determine what types of operations are feasible by comparing the force ratio with the historical minimum planning ratios for the contemplated combat missions (see Figure 3-10) and estimating the extent to which intangible factors affect the relative combat power. If, in the staff’s judgment, the relative combat power of the force produces the effects of the historical minimum-planning ratio for a contemplated mission, that mission is feasible.”

The element of surprise no doubt give the Americans greater relative effective combat power beyond their 1.6:1 advantage – which would not have violated even today’s doctrine.

I think the greater issue is not having people understand the rules and when to break them, but better understand doctrine and it’s purpose. Crack open those manuals and you’ll see that the doctrine itself provides frameworks of when it doesn’t apply. To say nothing of FM 3-0, which I’ve always read as the doctrine of leadership and audacity which super-cedes all other doctrine.


Gunslinger you reference the FM 5-0 and the FM 3-0, and I think you stumbled upon a really interesting point. The “Historical Minimum Planning Ratios” are only in the FM 5-0 Planning. It seems crazy that something that applies directly to Tactics and Operations is in a planning ratio.

Further, that ratio only accounts the raw number of troops. It leaves it up to the command to determine if “the relative combat power produces the effects of the historical minimum-planning ratio.” Frankly, this all but discounts the effects of all the principles of war and only relies on numbers.

But I think you misunderstand me. The Battle of Trenton didn’t require the 3:1 or 2.5:1 ratio of troops because of the element of surprise. Current doctrine supports that, but the vast majority of Officers and planners do not get that numbers are not what matters. I have never participated in an exercise where US forces did not have numerical superiority. I have never seen a command or planning staff argue that surprise or speed would influence a battle. I have never seen a serious discussion on the enemy’s morale and how to defeat it.

As you said, “doctrine itself provides frameworks of when it doesn’t apply.” The series of posts I am writing, of which this is the first, is to capture those ideas that many believe are doctrine but are not. The “3 to 1 advantage in the attack” which is how I always here it described, is a perfect example of a doctrinal idea being misapplied. The Washington example stands because the vast majority of maneuver planning staffs in the Army would never have approved that operation, they do not understand that numbers are only part of the story.


I don’t see that it discounts the effects of all the principles of war – I think that is what the authors (in, admittedly, poor prose) intend when they talk about “relative” combat power. I’ve always read that to mean the intangibles: superior weapon systems, morale and welfare of the troops, etc. I’ve always thought that it was the intent of the authors to say there are things that give you those ratios in effect, but not numerically. That may be just me, though. Also, while the rule is well known throughout the officer corps, to my knowledge that is the only manual that the 3-1 “rule” is actually stated. I may be wrong on that.

I’ll also disagree that exercises always have a U.S. numerical advantage. Two examples: the NTC (whose battalion here didn’t ever get run over by a regiment of OPFOR?) and the invasion of Iraq. The latter wasn’t just Rumsfeldian pipe-dreams. Our discussion of the enemy situation included their inferior weapons (exported T-72s mainly) and poor maintenance and conditions (food explicitly), our artillery and air support, and their horrible morale. That led to our platoons/troops conducting frontal attacks on dug-in elements of the Republican Guard at echelons to orders above our own (platoons on battalions, troops on brigades, etc). In effect, our “relative combat power” was most likely 3:1 or greater because of those intangibles, which for a planner/tactical leader would have sufficed to meet the doctrinal needs of an attack on prepared positions. But of course, that’s only a swag – based on the lower-level leadership and their understanding of the principles of war.


I don’t think we are really disagreeing. I agree that relative combat power analysis, in its ideal doctrinal form, is an analysis of fire power, technology, morale and other factors. And while that is what it meant to say, in practice it turns into a numbers thing with 3-1 being the golden rule.

As for the US always having the numerical advantage, except for NTC, the vast majority of exercises have the US in the offense out of the belief that the US is always attacking. As for NTC, it is funny that a regiment runs over a battalion, because again that is exactly the three to one ratio in manpower terms.

Iraq is the one place where you could argue we had a three to one advantage, but not in numbers but in technology and fire power. It is a good lesson to show that numbers are by no means everything, but I don’t think we have learned that lesson as an officer corps.

And for something as ubiquitous as the 3 to 1 combat power analysis, it is bizarre it is in the planning manual, not the tactics manual. It is a tactical principle but not mentioned in the tactics manual.