Grant, General of the Republican Guard
Once the United States Constitution had been destroyed by Northern radical revolutionaries, it could mean, and be interpreted, in any manner those backed by military power could imagine. After Andrew Johnson assumed the presidency, he thought he could create his own rules and recognize any assembly of Congress he desired, but found his control did not include the “Republican Guard” of Grant, Sherman and Sheridan. They would do the bidding of the victorious Radicals.
Bernhard Thuersam, Director
Cape Fear Historical Institute  

Grant, General of the Republican Guard:
General Grant told me a story of his own experience with [President Andrew Johnson]. Johnson, he said, had always been treated with such contempt and ignored socially by the members of the old families and slave aristocracy of the South that his resentment against them was vindictive, and so after the surrender at Appomattox he was constantly proclaiming “Treason is odious and must be punished.” He also wanted and, in fact, insisted upon ignoring Grant’s parole to the Confederate officers, in order that they might be tried for treason. On this question of maintaining his parole and his military honor General Grant was inflexible, and said he would appeal not only to Congress but to the country.
One day a delegation, consisting of the most eminent, politically, socially, and in family descent, of the Southern leaders, went to the White house. They said: “Mr. President, we have never recognized you, as you belong to an entirely different class from ourselves, but it is the rule of all countries and in all ages that supreme power vested in the individual raises him, no matter what his origin, to supreme leadership. You are now President of the United States, and by virtue of your office our leader, and we recognize you as such.” Then followed attention from these people whom he admired and envied, as well as hated, of hospitality and deference, of which they were past masters. It captivated him and changed his whole attitude towards them.
He sent for General Grant and said to him: “The war is over and there should be forgiveness and reconciliation. I propose to call upon all the States recently in rebellion to send to Washington their United States senators and members of the House, the same as they did before the war. If the present Congress will not admit them, a Congress can be formed of these southern senators and members of the house and of such Northern senators and representatives as will believe that I am right and acting under the Constitution. As President of the United States, I will recognize that Congress and communicate with them as such. As general of the army I want your support.”
General Grant replied: “That will create civil war, because the North will undoubtedly recognize the Congress as it now exists, and that Congress will assert itself in any way possible.” “In that case,” said the president, “I want the army to support the constitutional Congress which I am recognizing.” General Grant said: “On the contrary, so far as my authority goes, the army will support the Congress as it is now and disperse the other.”  President Johnson then ordered General Grant to Mexico on a mission, and as he had no power to send a general out of the United States, Grant refused to go. Shortly afterwards Grant received a very confidential communication from General Sherman, stating that he had been ordered to Washington to take command of the army, and wanted to know what it meant. General Grant explained the situation, whereupon General Sherman announced to the president that he would take exactly the same position as General Grant had. The president then dropped the whole subject.”
(My Memories of Eighty Years, Chauncey Depew, Charles Scribner’s Sons, 1924, pp. 49-51)