Grant became so absorbed in the conversation that Lee finally had to remind him of the business at hand

From a review, Muddy Boots and a Slouch Hat by Christopher Robbins in Slightly Foxed, Winter 2012. Robbins is describing Grant's history leading up to the amazing story of his Personal Memoirs. Grant failed at just about everything he turned his hand to except soldiering despite his antipathy for the cruelty of war. Having suffered economic ruin after his Presidency and then diagnosed with throat cancer, Grant determined to write his memoirs in the hope that they would provide a source of support for his soon to be widow. Urged on by Mark Twain who undertook to be his publisher, Grant set to work in late 1884, writing everyday, producing 20-50 pages a day, entirely from memory and with no assistance. He finished in July 1885 and died five days later. It became one of the best-selling books in American history.

One of my favorite passages in Memoirs is the description of Grant accepting the surrender of the Confederate Army's General Robert E. Lee. Grant rode over to the small house where Lee was installed, arriving as muddy and shabby as ever. Lee, on the other hand, was every inch the General, immaculate in a pale grey uniform with gold braided sleeves, a scarlet sash around his waist, a sword hanging at his side. Grant had left his sword behind - it got in the way when riding, he explained.

The admiration Grant felt for Lee almost amounted to a sense of awe and he did not attempt to hide it. As the staff prepared the surrender documents, the Generals chatted about the Mexican War and mutual military acquaintances. (Lee might have been surprised to learn that one of Grant's most trusted staff officers was a Native American.) Grant became so absorbed in the conversation that Lee finally had to remind him of the business at hand.

On an entirely different note, it reminds me of James Thurber's 1930 short story, If Grant Had Been Drinking at Appomattox. Five minutes well spent reading it.

"Shall we proceed at once to the matter in hand?" asked General Lee, his eyes disdainfully taking in the disordered room. "Some of the boys was wrassling here last night," explained Grant. "I threw Sherman, or some general a whole lot like Sherman. It was pretty dark." He handed a bottle of Scotch to the commanding officer of the Southern armies, who stood holding it, in amazement and discomfiture. "Get a glass, somebody," said Grant, looking straight at General Longstreet. "Didn't I meet you at Cold Harbor?" he asked. General Longstreet did not answer.

There's a Youtube version as well.