Was there an explicit three-to-one rule during the ACW for attacking an entrenched position?

Zack

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The next step of interpretation would be to look at the communications between officers prior to - say - the May 10 or May 12 assaults at Spotsylvania Courthouse, the assault at Franklin, the assault on Marye's Heights, etc. and see how the generals were discussing their plans. Do plans and dispatches show evidence of a desire to gain a 3:1 attacker to defender ratio?
 

Rhea Cole

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The next step of interpretation would be to look at the communications between officers prior to - say - the May 10 or May 12 assaults at Spotsylvania Courthouse, the assault at Franklin, the assault on Marye's Heights, etc. and see how the generals were discussing their plans. Do plans and dispatches show evidence of a desire to gain a 3:1 attacker to defender ratio?
I am not sure that there is anything analytical about Hood’s attack at Franklin.
 

Zack

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Fair enough lol. Maybe not Franklin.

In his Cold Harbor book (I'm on the google books version so no page number), Gordon Rhea writes in the section on June 3 how Union generals criticized Grant for launching massive, army-wide assaults rather than locating and exploiting an enemy weak point. Hancock's aide Walker said, "The characteristic fault of the campaign was attacking at too many points." Grant should "discover that weak point; to make careful and serious preparation for that attack, and to mass behind the assaulting column a force that shall be irresistible, if only once the line be pierced." Instead, Grant's attacks were "weak affairs in almost every case, unsupported; and mere shoving forward of a brigade or two now here now there, like a chess player shoving out his pieces and then drawing them right back."

Wainwright wrote that, "There may have been some plan in it, but in my ignorance I cannot help but think that one big, sustained attack at one point would have been much more likely to succeed."
 

Rhea Cole

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Fair enough lol. Maybe not Franklin.

In his Cold Harbor book (I'm on the google books version so no page number), Gordon Rhea writes in the section on June 3 how Union generals criticized Grant for launching massive, army-wide assaults rather than locating and exploiting an enemy weak point. Hancock's aide Walker said, "The characteristic fault of the campaign was attacking at too many points." Grant should "discover that weak point; to make careful and serious preparation for that attack, and to mass behind the assaulting column a force that shall be irresistible, if only once the line be pierced." Instead, Grant's attacks were "weak affairs in almost every case, unsupported; and mere shoving forward of a brigade or two now here now there, like a chess player shoving out his pieces and then drawing them right back."

Wainwright wrote that, "There may have been some plan in it, but in my ignorance I cannot help but think that one big, sustained attack at one point would have been much more likely to succeed."
I think you will find that Grant was doing his level best to instill an aggressive offensive spirit into the Army of the Potomac. He had also begun a ‘campaign of continuous contact,’ as modern military historians call it. It was the A of the P’s habit of contemplating their next move that gave Lee the initiative. Grant had no intention of chasing Lee around VA. His intent was to press Lee relentlessly to deprive him of any option but to respond to Grant’s pressure.

As Sherman said, Grant had no interest in what an opponent might do, he was only interested in what he was going to do to them. That the A of the P generals had a hard time wrapping their minds around what Grant was doing is no great surprise. A lot of deadwood had to be cleared out before the kind of relentless aggression Grant demanded could have effect.
 
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OldReliable1862

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I can't say for certain, but the three-to-one ratio may be derived from to the writings of Clausewitz, Jomini, Napoleon, or even Frederick the Great. All would probably have been familiar to West Pointers. I suspect that the ratio was based on the number of muzzle-loading weapons it would take to overcome a similarly armed and entrenched opponent. Perhaps someone with time on their hands could track it to one of these theorists.
The last three definitely, but Clausewitz would not be translated into English until 1873. Individual commanders may have been familiar with it, however.
 

Zack

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I think you will find that Grant was doing his level best to instill an aggressive offensive spirit into the Army of the Potomac. He had also begun a ‘campaign of continuous contact,’ as modern military historians call it. It was the A of the P’s habit of contemplating their next move that gave Lee the initiative. Grant had no intention of chasing Lee around VA. His intent was to press Lee relentlessly to deprive him of any option but to respond to Grant’s pressure.

As Sherman said, Grant had no interest in what an opponent might do, he was only interested in what he was going to do to them. That the A of the P generals had a hard time wrapping their minds around what Grant was doing is no great surprise. A lot of deadwood had to be cleared out before the kind of relentless aggression Grant demanded could have effect.

Haha - I'm not debating if Grant was justified in his tactics and strategies or not. I'm simply providing examples of officers suggesting some kind of desire to concentrate force against an entrenched line, perhaps to achieve a numerical superiority akin to the 3:1 rule. Perhaps it's simply the idea of hitting the weak part of the enemy's line with strength, or maybe it stems from officers' beliefs that dispersing force did not create enough of a local advantage to break through entrenchments.

Since we haven't found an explicit 3:1 comment, I'm looking for tangential references to the principle. I thought those quotes from Grant's officers seemed like a broad of saying "force parity is not enough against entrenchments, you need an advantage."

I have not read nearly enough to weigh in on a debate as to whether these officers were right or wrong in their assessment of Grant's tactics and strategy.

That being said, aggressive attitude seems more like a higher level "strategy" discussion than the nitty gritty of force ratios on the battlefield at the point of contact. One can fight aggressively while still launching concentrated attacks on the battlefield.
 

OldReliable1862

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I've pulled quotes from Jomini and Napoleon. Did Frederick the Great publish some sort of maxim/rules of war book? Maybe it's in there.
I haven't looked into Frederick, but from what I tell, I don't know if he produced any writings on military tactics.
 

Mark F. Jenkins

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The last three definitely, but Clausewitz would not be translated into English until 1873. Individual commanders may have been familiar with it, however.

Halleck mentioned Clausewitz in passing in his book Elements of Military Art and Science, but there's no question that Jomini dominated the field in the early-to-mid 19th century.
 

A. Roy

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Back in the day Vauban was criticized for his 6:1 "rule" because it was too dogmatic/artificial.

That's interesting. I've read smatterings of Vauban in secondary sources. Do you know where he propounded this rule? Was it in "A manual of siegecraft and fortification"? There is an English translation which is a little hard to get ahold of, but it is online in French.

[Later edit: I should have asked if you understood Vauban to have articulated a general rule, or whether this 6:1 ratio was in reference to a particular campaign or siege.]

R
 
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