What was the most significant event on April 1 during the U.S. Civil War?

I wasn't able to find conclusive evidence of when April Fools pranks started but it certainly existed during the civil war. Soldiers have had dark sense of humor as long as there have been wars. I can't begin to imagine what pranks were played in filed hospitals and with freshly dug graves.
I was impressed with Frederick Douglass challenge to free black me to enlist in the Union Army in the Spring of 1863.
In 1865 The resounding Union triumph at the Battle of Five Forks, VA heralded the end of the stalemate outside Petersburg and set the stage for the breakthrough that followed the next day. On April 2, Lee informed Jefferson Davis that Petersburg and Richmond would have to be evacuated. Lee surrendered to Grant only seven days later.
Since RallyPoint truncates survey selection text I am posting events that were not included and then the full text of each survey choice below:
1. Wednesday April 1, 1863: Confederate Lieutenant General James Longstreet’s command was reorganized to create the Department of North Carolina under Major General Daniel H. Hill, the Department of Richmond under Major General Arnold Elzey, and the Department of Southern Virginia under Major General S.G. French.
http://mncivilwar150.com/this-week-in-the-american-civil-war-april-1-7-1863/
2. Friday April 1, 1864: In Natchitoches, Louisiana, the Union force entered the town of Natchitoches. Once there, a small skirmish erupted between the Federals and the Confederate force. http://www.mycivilwar.com/battles/1864s.html
A. April 1, 1861: Abraham Lincoln decided how he would deal with the problem of Fort Sumter. Evacuation of both Fort Sumter and Fort Pickens to deny SC the justification to be privileged under the laws of war to resist an open confrontation.
President Lincoln Dupes the Confederates into Firing on Sumter ©
On Monday, April 1, 1861, Abraham Lincoln decided how he would deal with the problem of Fort Sumter. It was plain that an attempt to enter Charleston Harbor with military force would be recognized the world over as an act of hostility by the United States against South Carolina, that the State would be privileged under the laws of war to resist. It was exactly this outcome that William H. Seward had been adamant in arguing, over the last two weeks, Lincoln should avoid.
Just three days earlier, at a Cabinet meeting, Seward’s policy seemed to be accepted, when General Scott formally opined that both Fort Sumter and Fort Pickens be evacuated. Backing Scott up, Seward had stressed the point that the dispatch of an expedition to Charleston “would provoke an attack and so involve war at that point." Seward had tried to bolster his case with the concession that, while Sumter should be evacuated, Pickens should be held— suggesting that Captain M.C. Meigs could organize an expedition to relieve Pickens.
Lincoln responded, by giving Seward the choice of either having the expedition to Charleston result in a collision of arms, as Lincoln already had Gustavus V. Fox organizing it, or help Lincoln derail it without any one knowing.
Accepting the fact he could not move Lincoln to his view, Seward agreed to participate. Working hand-in-hand now with Seward, Lincoln wrote the following messages on Monday, April 1.
No originals of these messages have come down to us. There are more than one version of some of them, written by different persons. None of the messages in the record are in Lincoln’s hand, but their essential accuracy is confirmed by David D. Porter who received them from Lincoln’s hand and carried them to New York. (Porter does not tell us what he did with the order addressed to him.)
http://americancivilwar.com/authors/Joseph_Ryan/150-Year-Anniversary/April-1861/What-Happened-in-April-1861.html
Executive Mansion, April 1, 1861; to Commandant Andrew H. Foote, commanding Brooklyn Navy Yard
Sir: You will fit out the Powhatan without delay. Lieutenant Porter will relieve Captain Mercer in command of her. She is bound for secret service, and you will under no circumstances communicate to the Navy Department the fact that she is putting out. Abraham Lincoln
http://americancivilwar.com/authors/Joseph_Ryan/150-Year-Anniversary/April-1861/What-Happened-in-April-1861.html
Executive Mansion, April 1, 1861 to Captain Samuel Mercer, U.S. Navy
Sir: Circumstances render it necessary to place in command of your ship, and for a special purpose, an officer who is duly informed and instructed in relation to the wishes of the Government, and you will therefore consider yourself detached.
Abraham Lincoln
http://americancivilwar.com/authors/Joseph_Ryan/150-Year-Anniversary/April-1861/What-Happened-in-April-1861.html
Executive Mansion, April 1, 1861 to Lieutenant David D. Porter
Sir: You will proceed to New York, and with the least possible delay assume command of the Powhatan. Proceed to Pensacola Harbor, and at any cost prevent any Confederate expedition from the mainland reaching Fort Pickens. This order, its object, and your destination will be communicated to no person whatever until you reach the harbor of Pensacola.
Abraham Lincoln
http://americancivilwar.com/authors/Joseph_Ryan/150-Year-Anniversary/April-1861/What-Happened-in-April-1861.html
Tuesday April 1, 1862:
B Wednesday April 1, 1863: In Douglass’ Monthly, Frederick Douglass publishes this editorial by himself about the need for black men to join the Union Army:
First. You are a man, although a colored man. If you were only a horse or an ox, incapable of deciding whether the rebels are right or wrong, you would have no responsibility, and might like the horse or the ox go on eating your corn or grass, in total indifference, as to which side is victorious or vanquished in this conflict. You are however no horse, and no ox, but a man, and whatever concerns man should interest you. He who looks upon a conflict between right and wrong, and does not help the right against the wrong, despises and insults his own nature, and invites the contempt of mankind. As between the North and South, the North is clearly in the right and the South is flagrantly in the wrong. You should therefore, simply as a matter of right and wrong, give your utmost aid to the North. In presence of such a contest there is no neutrality for any man. . . .
Second. You are however, not only a man, but an American citizen, so declared by the highest legal adviser of the Government, and you have hitherto expressed in various ways, not only your willingness but your earnest desire to fulfil any and every obligation which the relation of citizenship imposes. Indeed, you have hitherto felt wronged and slighted, because while white men of all other nations have been freely enrolled to serve the country, you a native born citizen have been coldly denied the honor of aiding in defense of the land of your birth. . . .
Third. A third reason why a colored man should enlist is found in the fact that every Negro-hater and slavery-lover in the land regards the arming of Negroes as a calamity and is doing his best to prevent it. . . .
Fourth. You should enlist to learn the use of arms, to become familiar with the means of securing, protecting and defending your own liberty. A day may come when men shall learn war no more, when justice shall be so clearly apprehended, so universally practiced, and humanity shall be so profoundly loved and respected, that war and bloodshed shall be confined only to beasts of prey. . . . When it is seen that black men no more than white men can be enslaved with impunity, men will be less inclined to enslave and oppress them. Enlist therefore, that you may learn the art and assert the ability to defend yourself and your race.
Fifth. You are a member of a long enslaved and despised race. Men have set down your submission to Slavery and insult, to a lack of manly courage. They point to this fact as demonstrating your fitness only to be a servile class. You should enlist and disprove the slander, and wipe out the reproach. When you shall be seen nobly defending the liberties of your own country against rebels and traitors— brass itself will blush to use such arguments imputing cowardice against you.
Sixth. Whether you are or are not, entitled to all the rights of citizenship in this country has long been a matter of dispute to your prejudice. By enlisting in the service of your country at this trial hour, and upholding the National Flag, you stop the mouths of traducers and win applause even from the iron lips of ingratitude. Enlist and you make this your country in common with all other men born in the country or out of it.
Seventh. Enlist for your own sake. Decried and derided as you have been and still are, you need an act of this kind by which to recover your own self-respect. You have to some extent rated your value by the estimate of your enemies and hence have counted yourself less than you are. You owe it to yourself and your race to rise from your social debasement. . . .
Eighth. You should enlist because your doing so will be one of the most certain means of preventing the country from drifting back into the whirlpool of Pro-Slavery Compromise at the end of the war, which is now our greatest danger. He who shall witness another Compromise with Slavery in this country will see the free colored man of the North more than ever a victim of the pride, lust, scorn and violence of all classes of white men. . . .
Ninth. You should enlist because the war for the Union, whether men so call it or not, is a war for Emancipation. The salvation of the country, by the inexorable relation of cause and effect, can be secured only by the complete abolition of Slavery. The President has already proclaimed emancipation to the Slaves in the rebel States which is tantamount to declaring Emancipation in all the States, for Slavery must exist everywhere in the South in order to exist anywhere in the South. Can you ask for a more inviting, ennobling and soul enlarging work, than that of making one of the glorious Band who shall carry Liberty to your enslaved people? . . .
When time's ample curtain shall fall upon our national tragedy, and our hillsides and valleys shall neither redden with the blood nor whiten with the bones of kinsmen and countrymen who have fallen in the sanguinary and wicked strife; when grim visaged war has smoothed his wrinkled front and our country shall have regained its normal condition as a leader of nations in the occupation and blessings of peace—and history shall record the names of heroes and martyrs who bravely answered the call of patriotism and Liberty—against traitors, thieves and assassins—let it not be said that in the long list of glory, composed of men of all nations—there appears the name of no colored man.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=April+1%2C+1863
C April 1, 1864: This is an original Thomas Nast illustration from the April 2, 1864 edition of Harper's Weekly. The illustration features about a dozen images of April Fool's day pranks. The illustration is captioned, "All Fool's Day", and shows Thomas Nast's distinctive signature in the lower right of the center image.
Some of the pranks illustrated in this 1864 picture include women paying a visit to an older man, with the women wearing beards and moustaches. Another image shows Civil War Soldiers playing April Fool's tricks on one another. In one case, a soldier is seen holding his hand on in front of the binoculars of a friend, and in another case, a sailor is seen holding his hat over the telescope of a friend. In one of the lower images, a young boy can be seen tying a string on the dress of a little girl, and in another image a school teacher is seen with a sign on his back that says "Old Fool". Overall this is an extremely interesting piece of artwork, showing the April Fool's traditions of 1864.
D April 1, 1865: Battle of Five Forks
In the spring of 1865, Lt. Gen. Ulysses S. Grant had an opportunity to force Gen. Robert E. Lee's Army of Northern Virginia out of its entrenchments at Petersburg by threatening its last supply line, the South Side Railroad. Grant ordered Maj. Gen. Phil Sheridan and his cavalry to advance on the railroad by way of an important road junction known as Five Forks. Lee countered this move by ordering Maj. Gen. George Pickett with his infantry division and cavalry under Thomas Munford, W.H.F. Lee, and Thomas Rosser to hold the vital crossroads "at all hazards." After discovering the Confederate force, Sheridan secured infantry support from Maj. Gen. Gouverneur K. Warren's Fifth Corps. After briefly stalling the Union advance on March 31, Pickett withdrew his command to Five Forks and fortified his position. The next day, while Sheridan’s cavalry pinned the Confederates in position, the Fifth Corps assaulted the Confederate left flank and rear, turning their position and taking scores of prisoners. Pickett, who was attending a shad bake when the fighting began, was unaware that a battle was underway until it was too late. Sheridan, meanwhile, personally directed the Union attack, often exposing himself to personal danger while rallying the troops. Union Brig. Gen. Frederick Winthrop was killed; “Willie” Pegram, beloved Confederate artillery officer, was mortally wounded. Though the Fifth Corps had performed well, Sheridan was nevertheless dissatisfied Warren's performance during the battle and relieved him of command.
The resounding Union triumph heralded the end of the stalemate outside Petersburg and set the stage for the breakthrough that followed the next day. On April 2, Lee informed Jefferson Davis that Petersburg and Richmond would have to be evacuated. Lee surrendered to Grant only seven days later.
http://www.civilwar.org/battlefields/five-forks.html
COL Mikel J. Burroughs LTC Stephen C. LTC (Join to see) CSM Charles Hayden SFC William Swartz Jr SGM Steve Wettstein SP6 Clifford Ward PO1 John Miller PO2 William Allen Crowder SGT Randal Groover SrA Christopher Wright SGT John " Mac " McConnell SP5 Mark Kuzinski SPC Corbin Sayi SSgt (Join to see) SSgt Robert Marx SPC (Join to see) CPO Tim Dickey SGT (Join to see) CW5 (Join to see)

LTC Stephen F. thanks for posting Civil War History, I am at awe with all the history on this date which is April Fools Day and I know it can be challenging. Thanks as usual for this compelling historic Civil War thread, I look forward to more of it. I really enjoy your post!

Great read LTC Stephen F. .