On April 9, 1865, Robert E. Lee agreed to Ulysses S. Grant's surrender terms at Appomattox Court House.

Their negotiations began two days earlier through an exchange of letters. 

You can read the entirety of their correspondence at the Civil War Trust's website. All told, the correspondence consisted of eight letters--four alternating messages from each general. Here are seven negotiation pointers you can glean from those letters:

1. Make an aggressive opening gambit. As Robb Mandelbaum points out in his timeless list of negotiation tips, "a growing body of evidence suggests that a well-prepared first mover has the advantage."

The reason? The opening terms can anchor the negotiation--setting the baseline for acceptable terms. Of course, the risk is setting a baseline so preposterous you alienate your counterpart. So the key is anchoring your opening in the reality of common ground. 

What this requires is knowledge of what your counterpart will accept. Grant, for his part, believed Lee's "once vaunted Army of Northern Virginia was dissolving," notes the Civil War Trust. So he opened negotiations by plainly asking Lee--commander of the Army of Northern Virginia--for his surrender: 

General R. E. LEE: The result of the last week must convince you of the hopelessness of further resistance on the part of the Army of Northern Virginia in this struggle. I feel that it is so, and regard it as my duty to shift from myself the responsibility of any further effusion of blood, by asking of you the surrender of that portion of the C. S. Army known as the Army of Northern Virginia.

2. Keep it brief and direct. Observe how Grant comes right to the point. His letter is two sentences long. The first is a summary of recent events; the second is his official "ask."

Today's leaders too can benefit from such brevity and directness in their written correspondence.

"If you want a response, make sure you ask for something specific," notes Paul Jarvis in his fantastic primer on composing effective emails. "Don't use open-ended questions or pussyfoot around because you're too scared to ask something." 

3. Don't say yes to the first offer. With brevity and directness matching Grant's, Lee essentially said, No, thank you--but tell me more: 

Lieut. Gen. U.S. GRANT: I have received your note of this date. Though not entertaining the opinion you express on the hopelessness of further resistance on the part of the Army of Northern Virginia, I reciprocate your desire to avoid useless effusion of blood, and therefore, before considering your proposition, ask the terms you will offer on condition of its surrender.

Lee illustrated another principle of effective negotiations: Deny the first offer, since the offerer is just trying to anchor terms. 

"The fact is, most negotiators make an initial offer that is lower than the number that they are prepared to settle for--it's just an expected part of the negotiation game," notes Peter Economy in his recent compilation of dealmaking pointers. 

4. Emphasize the common ground. Repeatedly. In this case, the common ground was avoiding the "useless effusion of blood." Both Grant in his initial outreach and Lee in his first reply affirmed this as the common ground. Grant returns to the common ground as he replies to Lee with terms: 

General R. E. LEE: Your note of last evening, in reply to mine of same date, asking the condition on which I will accept the surrender of the Army of Northern Virginia, is just received. In reply I would say that, peace being my great desire, there is but one condition I would insist upon, namely, that the men and officers surrendered shall be disqualified for taking up arms again against the Government of the United States until properly exchanged. I will meet you, or will designate officers to meet any officers you may name for the same purpose, at any point agreeable to you, for the purpose of arranging definitely the terms upon which the surrender of the Army of Northern Virginia will be received.

Once you find common ground, it can serve as a baseline from which both parties can proceed to the difficult parts of the negotiation. Sports agent Molly Fletcher told Inc. that finding common ground can alleviate "that simple fear of failure that can stall or stop the process even from the start."

5. Agree to speak in real time and to meet in person. Note how Grant concludes his reply by offering to meet at a location of Lee's choice.

You can find all sorts of evidence--statistical and anecdotal--for how real-time communication abets negotiations. For example, as Inc.com columnist Samuel Bacharach points out, President Obama spent nearly one hour on the phone with Fidel Castro during negotiations with Cuba. 

"While we know nothing about the conversation," he writes, "it is safe to say that a phone meeting helped relations more than any paperwork. It began a conversation and a relationship."

Likewise, the element of actual face time--as opposed to phone calls or virtual chats--can help build trust. My colleague Laura Montini recently posted a fantastic infographic illustrating how crucial elements of face-to-face meetings--handshakes and subtleties of body language--still matter when it comes to the preservation of business relationships. 

6. Meet at a neutral site. In his next letter, Lee proposed a neutral location to Grant--making it plain that his agreement to meet did not constitute a surrender:

Lieut. Gen. U.S. GRANT: I received at a late hour your note of to-day. In mine of yesterday I did not intend to propose the surrender of the Army of Northern Virginia, but to ask the terms of your proposition. To be frank, I do not think the emergency has arisen to call for the surrender of this army, but as the restoration of peace should be the sole object of all, I desired to know whether your proposals would lead to that end. I cannot, therefore, meet you with a view to surrender the Army of Northern Virginia, but as far as your proposal may affect the C. S. forces under my command, and tend to the restoration of peace, I should be pleased to meet you at 10 a.m., to-morrow; on the old stage road to Richmond, between the picket-lines of the two armies.

Note how Lee rephrases yet continues stressing the common ground--he calls it "the restoration of peace." In addition, you can see how their correspondence--while still brief--has lengthened, now that they're talking terms. 

As for the neutral site, Bacharach points out that this is another smart tactic U.S. officials used in their negotiations with Cuba. "President Obama and Cuban officials met in Canada--neutral ground--for the first round of talks," he notes. Later talks took place at the Vatican.

7. Make sure you can deliver your end of the agreement. In agreeing to meet with Lee at the neutral location, Grant was clear that he himself did not have the unilateral authority to deliver peace. He nevertheless stressed to Lee that their meeting could "hasten" the process:

General R. E. LEE: Your note of yesterday is received. I have no authority to treat on the subject of peace; the meeting proposed for 10 a.m. to-day could lead to no good. I will state, however, general, that I am equally anxious for peace with yourself, and the whole North entertains the same feeling. The terms upon which peace can be had are well understood. By the South laying down their arms they will hasten that most desirable event, save thousands of human lives, and hundreds of millions of property not yet destroyed. Seriously hoping that all our difficulties may be set-tied without the loss of another life, I subscribe myself, &c.,

The lesson here is not to promise what you can't deliver. Hillary Clinton learned this the hard way during the State Department's tense negotiations with China on behalf of dissident Chen Guangcheng. 

Once China and the U.S. agreed on a solution--Chen would go to law school--there only remained the matter of getting Chen himself to sign off on it. Though Chen had previously agreed to the plan, he now had second thoughts. "He wanted to speak with his family and have them come to Beijing before making any final decisions," writes Clinton in Hard Choices.

The bottom line: Negotiating terms is one thing; executing terms is quite another. The upshot is to be honest about what you have the power to execute. That's what Grant did, 150 years ago. He and Lee exchanged three more letters. And then the surrender of the Army of Northern Virginia was complete.