What was the most significant event on May 18 during the U.S. Civil War?

Saturday, May 18, 1861: Battle of Sewell’s point, Virginia. Inconclusive. Two Union gunboats, including USS Monticello, dueled with Confederate batteries on Sewell’s Point in an attempt to enforce the blockade of Hampton Roads. The two sides did each other little harm.
Sunday, May 18, 1862: Citizens of the small Virginia town of Suffolk are on their way to church when Union cavalry appear. A mother and child take note of the arrival of the blue-coated mounted troops, with the boy raising his cap and shouting, “Hurrah for Jeff Davis!” The Union commander rides over, wags his finger gently in the lad’s direction and admonishes, “You little traitor,” as the mortified parent grabs her child and races for the security of their home. The war has hit home for this previously quiet community.
Sunday, May 18, 1862: Mary Boykin Chestnut of South Carolina writes in her diary: “Norfolk has been burned and the Merrimac sunk without striking a blow since her coup d’état in Hampton Roads. Read Milton. See the speech of Adam to Eve in a new light. Women will not stay at home; will go out to see and be seen, even if it be by the devil himself.
Very encouraging letters from Hon. Mr. Memminger and from L. Q. Washington. They tell the same story in very different words. It amounts to this: "Not one foot of Virginia soil is to be given up without a bitter fight for it. We have one hundred and five thousand men in all, McClellan one hundred and ninety thousand. We can stand that disparity." . . .
There is said to be an order from Butler turning over the women of New Orleans to his soldiers. Thus is the measure of his iniquities filled. We thought that generals always restrained, by shot or sword if need be, the brutality of soldiers. This hideous, cross-eyed beast orders his men to treat the ladies of New Orleans as women of the town—to punish them, he says, for their insolence.
Footprints on the boundaries of another world once more. Willie Taylor, before he left home for the army, fancied one day—day, remember—that he saw Albert Rhett standing by his side. He recoiled from the ghostly presence. "You need not do that, Willie. You will soon be as I am." Willie rushed into the next room to tell them what had happened, and fainted. It had a very depressing effect upon him. And now the other day he died in Virginia.”
Pictures: 1861 Rebel batteries Sewell’s point harper's weekly 11-2-1861; 1863 Ulysses S. Grant, as photographed by Mathew B. Brady; Journal writer Mary Boykin Chestnut; 1862 Admiral David G. Farragut
Since RallyPoint truncates survey selection text I am posting events that were not included and then the full text of each survey choice below:
A. Sunday, May 18, 1862: Vicksburg, Mississippi. Initial efforts by Union land and naval forces to capture Vicksburg and open the great waterway to navigation ended in failure. The first threat developed on May 18, 1862, when the ships of the West Gulf Blockading Squadron arrived below Vicksburg and the Federals made a demand for the city's surrender. In terse words the demand was refused. Lieutenant Colonel James L. Autry, the post commander, replied, "Mississippians don't know, and refuse to learn, how to surrender to an enemy." Incensed, Federal authorities opened fire upon the city and maintained an intermittent bombardment from late May, all through June, and into late July, but to no avail. The bombardment was ineffective and Farragut's fleet, wracked with sickness and plagued by rapidly falling waters, withdrew to New Orleans and deeper waters.
Background: Moving upriver from the Gulf of Mexico were the ships of the West Gulf Blockading Squadron commanded by Flag Officer David Glasgow Farragut. His ships bombarded and passed Forts Jackson and St. Philip on April 24 and compelled the surrender of New Orleans. With initial success behind him, Farragut sent an advance flotilla upriver. Baton Rouge fell to the Federals on May 8, Natchez four days later, and the flotilla steamed on toward Vicksburg.
B. Monday, May 18 1863: Union General Ulysses S. Grant’s Army of Tennessee surrounds Vicksburg, Mississippi the last Confederate stronghold on the Mississippi River, in one of the most brilliant campaigns of the war. CSA Lt. Gen. John Pemberton ignored Gen. Joseph E. Johnston instruction, after the battle of Champion Hill to abandon Vicksburg because “between saving the city and saving the army, he must save the army, and that if he is trapped in Vicksburg, he will have to surrender and lose both, since Johnston does not have the means to raise the siege that surely must ensue.” In answer, Pemberton writes this letter, with a strange argument that abandoning Vicksburg will make his 30,000 men unfit for service: that they will then lack “such morale and material as to be of further service to the Confederacy.”
C. Wednesday, May 18, 1864 Battle of Spotsylvania, Day 10 – Harris Farm: After fighting for several days in continuous rain, Lt Gen U.S. Grant’s troops were too exhausted to undertake another assault against the Confederate lines guarding the Spotsylvania Court House. Grant re-orders his lines, and conceives of a plan to send one corps marching to his left down the railroad to Richmond, and hoping that Lee will take the bait and follow this corps, while Grant follows, in the hopes of catching Lee in a trap. He plans to put this in to effect on the morning of the 19th.
D. Wednesday, May 18, 1864: Skirmish at Woodlands, Georgia. Situated directly in the path of Sherman's advance, the Barnsley Gardens and Resort estate witnesses a battle on May 18, 1864 and suffers irreparably during occupation of troops commanded by U.S. Gen. James McPherson.
1. May 18, 1860: Republican Convention is held in Chicago, Illinois from May 16-18, 1860. William H. Seward, Salmon P. Chase and Abraham Lincoln of Illinois are the leading contenders from a field of 12 candidates. Lincoln wins on the third ballot. Hannibal Hamlin of Maine, an outspoken, long-time abolitionist is chosen for vice-president.
http://blueandgraytrail.com/year/1860
2. Saturday, May 18, 1861: Arkansas was officially admitted to the Confederacy with their Congressman taking their seats at Montgomery.
http://www.wplucey.com/2011/01/us-civil-war-150th-anniversary-reference-guide.html
3. Saturday, May 18, 1861: Battle of Sewell’s point, Virginia. Inconclusive. Two Union gunboats, including USS Monticello, dueled with Confederate batteries on Sewell’s Point in an attempt to enforce the blockade of Hampton Roads. The two sides did each other little harm. Principal Commanders: Lt. D.L. Braine U.S.N. [US]; Brig. Gen. Walter Gwynn and Capt. Peyton Colquitt [CS] Estimated Casualties: 10 total.
http://www.civilwarguide.info/battles/battle-of-sewells-point/
4. Sunday, May 18, 1862: At Vicksburg, Mississippi, Flag Officer David Farragut demands the surrender of the city and its fortifications. Maj. Gen. Smith, in command, sends back the reply that Mississippians do not know how to surrender. Farragut does not have any choice, since the heavy guns at Vicksburg are two hundred feet high on the bluffs, and can fire down on them, whereas the naval guns cannot elevate to shoot that high. Vicksburg is garrisoned with 8,000 troops, and Farragut has only about 1,000 with him.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1862
5. Sunday, May 18, 1862 --- Gen. Halleck’s Grand Army (actually being commanded in the field by Gen. Pope) has moved 3 miles in ten days, toward Corinth. Halleck sends a dispatch in hopeful tones to the effect that his "whole line moved up yesterday to within 2 miles of enemy’s works, driving back their advance guards, which made strong resistance. . . ."
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1862
6. Sunday, May 18, 1862: Citizens of the small Virginia town of Suffolk are on their way to church when Union cavalry appear. A mother and child take note of the arrival of the blue-coated mounted troops, with the boy raising his cap and shouting, “Hurrah for Jeff Davis!” The Union commander rides over, wags his finger gently in the lad’s direction and admonishes, “You little traitor,” as the mortified parent grabs her child and races for the security of their home. The war has hit home for this previously quiet community.
http://cwc.hss.kennesaw.edu/timeline/timeline_1862/
7. Sunday, May 18, 1862 --- Surgeon Castleman records an incident similar to yesterdays, but much worse, of Gen. McClellan’s timidity about advancing: Last night, after we had retired, the aids-de-camp of the several brigades, rode through the camp, and calling up the company commanders, read aloud: "Orders from Headquarters. Roll will beat at 5 in the morning. Army will move at half-past six, precisely." All was bustle. The chests and boxes which had yesterday been packed for a move, in the morning, Unpacked in the afternoon, were again packed at night, which showed how eager our soldiers are to get to work. The roll, at 5 this morning, instead of calling them from their beds, summoned them to breakfast. They were ready, but had not finished their hurriedly prepared meal, when it was announced through the camp, "Order of last night, to move this morning, is countermanded." If the oaths then perpetrated were recorded in heaven, the recording angel would certainly have been justified had he have "dropped a tear upon the page and blotted them out forever." Our army swore terribly, but their ruffled feelings are now being calmed by the beautiful notes of Old Hundred, exquisitely performed by our band, and recalling, oh! how many sweet recollections of homes where many of us have, for the last time, had the warring elements of our souls soothed into quiet submission by the "peace, be still," of this master piece of sacred music.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1862
8. Sunday, May 18, 1862 --- Mary Boykin Chestnut of South Carolina writes in her diary: Norfolk has been burned and the Merrimac sunk without striking a blow since her coup d’état in Hampton Roads. Read Milton. See the speech of Adam to Eve in a new light. Women will not stay at home; will go out to see and be seen, even if it be by the devil himself.
Very encouraging letters from Hon. Mr. Memminger and from L. Q. Washington. They tell the same story in very different words. It amounts to this: "Not one foot of Virginia soil is to be given up without a bitter fight for it. We have one hundred and five thousand men in all, McClellan one hundred and ninety thousand. We can stand that disparity." . . .
There is said to be an order from Butler turning over the women of New Orleans to his soldiers. Thus is the measure of his iniquities filled. We thought that generals always restrained, by shot or sword if need be, the brutality of soldiers. This hideous, cross-eyed beast orders his men to treat the ladies of New Orleans as women of the town—to punish them, he says, for their insolence.
Footprints on the boundaries of another world once more. Willie Taylor, before he left home for the army, fancied one day—day, remember—that he saw Albert Rhett standing by his side. He recoiled from the ghostly presence. "You need not do that, Willie. You will soon be as I am." Willie rushed into the next room to tell them what had happened, and fainted. It had a very depressing effect upon him. And now the other day he died in Virginia.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1862
9. Monday, May 18 1863 --- Gen. Joseph E. Johnston, the titular chief of this department, writes to Lt. Gen. John C. Pemberton after the battle of Champion Hill, urging Pemberton to abandon Vicksburg---that between saving the city and saving the army, he must save the army, and that if he is trapped in Vicksburg, he will have to surrender and lose both, since Johnston does not have the means to raise the siege that surely must ensue. In answer, Pemberton writes this letter, with a strange argument that abandoning Vicksburg will make his 30,000 men unfit for service: that they will then lack “such morale and material as to be of further service to the Confederacy”:
HDQRS. DEPARTMENT OF Mississippi AND EASTERN LOUISIANA, Vicksburg, May 18, 1863.
General JOSEPH E. Johnston: GENERAL: I have the honor to acknowledge the receipt of your communication, in reply to mine by the hands of Captain [Thomas] Henderson. In a subsequent letter of same date as this latter, I informed you that the men had failed to hold the trenches at Big Black Bridge, and that, as a consequence, Snyder's Mill was directed to be abandoned. On the receipt of your communication, I immediately assembled a council of war of the general officers of this command, and having laid your instructions before them, asked the free expression of their opinions as to the practicability of carrying them out. The opinion was unanimously expressed that it was impossible to withdraw the army from this position with such morale and material as to be of further service to the Confederacy. While the council of war was assembled, the guns of the enemy opened on the works, and it was at the same time reported that they were crossing the Yahoo River at Brandon's Ferry, above Snyder's Mill. I have decided to hold Vicksburg as long as is possible, with the firm hope that the Government may yet be able to assist me in keeping this obstruction to the enemy's free navigation of the Mississippi River. I still conceive it to be the most important point in the Confederacy.
Very respectfully, your obedient servant,\ J. C. PEMBERTON, Lieutenant-General, Commanding.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1863
10. Monday, May 18 1863 --- Gen. McClernand gets his engineers to throw a pontoon bridge across the Big Black, and his troops march over. Farther upstream, Grant has McPherson cross and Sherman even farther upstream. The road to Vicksburg is open, and it is only 12 miles away. By nightfall, McClernand’s troops are only 4 miles from Vicksburg, and McPherson and Sherman are close at hand and link up in a line that covers at least ¾ of the Vicksburg defenses. The Siege of Vicksburg is underway.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1863
11. Monday, May 18 1863 --- Sergeant Osborn H. Oldroyd, of the 20th Ohio Infantry Regiment, writes in his journal of the victorious advance of Grant’s troops over the Big Black, and their quick pace in closing up the trap at Vicksburg: As we crossed the river and marched up the bank, a brass band stood playing national airs. O, how proud we felt as we marched through the rebel works, and up to the muzzles of the abandoned guns that had been planted to stay our progress. Every man felt the combined Confederate army could not keep us out of Vicksburg. It was a grand sight, the long lines of infantry moving over the pontoons, and winding their way up the bluffs, with flags flying in the breeze, and the morning sun glancing upon the guns as they lay across the shoulders of the boys. Cheer after cheer went up in welcome and triumph from the thousands who had already crossed and stood in waiting lines upon the bluff above. This is supposed to be the last halting place before we knock for admittance at our goal—the boasted Gibraltar of the west.
Our division has made a long march to-day, and we have bivouaced for the night without supper, and with no prospect of breakfast, for our rations have been entirely exhausted. Murmurings and complaints are loud and deep, and the swearing fully up to the army standard.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1863
12. Monday, May 18 1863 --- News apparently does not travel as accurately as desired in the South. The Daily Journal of Wilmington, North Carolina publishes an editorial that is patently wrong about the fortunes of Grant’s Yankee army in central Mississippi: The news received to-day by telegraph is less discouraging than any we have had for some days past. At last we get something from Jackson and the West. As we knew, Jackson was entered last week by the Federals. It would seem that they must have been checked in their advance, as they are retreating, after having done much damage. It is to be hoped that they will be made to regret their sudden advance into the interior. Vicksburg and Port Hudson still stand and the enemy’s base and communications are threatened. We shall look for further news from that quarter with much interest.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1863
13. Monday, May 18 1863 --- The U.S. Secretary of the Navy, Gideon Welles, writes in his journal about some common reservations about Gen. Joseph Hooker’s moral liabilities: Senator Doolittle came to see me to-day. Has faith, he says, but fears that General Hooker has no religious faith, laments the infirmities of that officer, and attributes our late misfortune to the want of godliness in the commanding general.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1863
14. Monday, May 18 1863 --- In Britain, in the House of Lord, the Marquis of Clanricarde charges that the United States has been lax and even flawed in respecting the rights of British ship owners of ships seized by the U.S Navy in the course of blockade duty. The Foreign Secretary, the Earl Russell, makes a speech in reply, saying that the Crown has investigated such claims and so far can find no legal fault with the way the Union has dealt with British ships. Russell goes on to categorically deny Crown complicity in the escape of the CSS Alabama (built in Liverpool) from British waters, and that Britain has no desire to interfere unfairly in the Civil War in America.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1863
15.

A Sunday, May 18, 1862: Vicksburg, Mississippi. Initial efforts by Union land and naval forces to capture Vicksburg and open the great waterway to navigation ended in failure. The first threat developed on May 18, 1862, when the ships of the West Gulf Blockading Squadron arrived below Vicksburg and the Federals made a demand for the city's surrender. In terse words the demand was refused. Lieutenant Colonel James L. Autry, the post commander, replied, "Mississippians don't know, and refuse to learn, how to surrender to an enemy." Incensed, Federal authorities opened fire upon the city and maintained an intermittent bombardment from late May, all through June, and into late July, but to no avail. The bombardment was ineffective and Farragut's fleet, wracked with sickness and plagued by rapidly falling waters, withdrew to New Orleans and deeper waters.
Background: Moving upriver from the Gulf of Mexico were the ships of the West Gulf Blockading Squadron commanded by Flag Officer David Glasgow Farragut. His ships bombarded and passed Forts Jackson and St. Philip on April 24 and compelled the surrender of New Orleans. With initial success behind him, Farragut sent an advance flotilla upriver. Baton Rouge fell to the Federals on May 8, Natchez four days later, and the flotilla steamed on toward Vicksburg.
http://www.civilwar.org/battlefields/vicksburg/vicksburg-history-articles/vicksburgwinshcelhg.html
B Monday, May 18 1863: The siege of Vicksburg (Mississippi) begins by Gen. Ulysses Grant’s Army of Tennessee, entrapping the Confederate Army under Lt. Gen. John Pemberton.
http://www.wplucey.com/2011/01/us-civil-war-150th-anniversary-reference-guide.html
B+ Monday, May 18 1863: Union General Ulysses S. Grant surrounds Vicksburg, the last Confederate stronghold on the Mississippi River, in one of the most brilliant campaigns of the war.
Beginning in the winter of 1862-63, Grant made several attempts to capture Vicksburg. In March, he marched his army down the west bank of the Mississippi, while Union Admiral David Porter’s flotilla ran past the substantial batteries that protected the city. They met south of the city, and Grant crossed the river and entered Mississippi. He then moved north to approach Vicksburg from its more lightly defended eastern side. In May, he had to split his army to deal with a threat from Joseph Johnston’s Rebels in Jackson, the state capital that lay 40 miles east of Vicksburg. After defeating Johnston’s forces, Grant moved toward Vicksburg.
On May 16, Grant fought the Confederates under John C. Pemberton at Champion Hill and defeated them decisively. He then attacked again at the Big Black River the next day, and Pemberton fled into Vicksburg with Grant following close behind. The trap was now complete and Pemberton was stuck in Vicksburg, although his forces would hold out until July 4.
In the three weeks since Grant crossed the Mississippi in the campaign to capture Vicksburg, his men marched 180 miles and won five battles. They took nearly 100 Confederate artillery pieces and nearly 6,000 prisoners, all with relatively light losses.
http://www.history.com/this-day-in-history/the-siege-of-vicksburg-commences
C Wednesday, May 18, 1864 --- Battle of Spotsylvania, Day 10: Very little happens today on the respective armies’ fronts. Grant re-orders his lines, and conceives of a plan to send one corps marching to his left down the railroad to Richmond, and hoping that Lee will take the bait and follow this corps, while Grant follows, in the hopes of catching Lee in a trap. He plans to put this in execution tomorrow.
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=may+18%2C+1864
C+ Wednesday, May 18, 1864: Battle of Spotsylvania, Day 10 – Harris Farm: After fighting for several days in continuous rain, Grant’s troops were too exhausted to undertake another assault against the Confederate lines guarding the Spotsylvania Court House. The last ditch attempt to take the Mule Shoe, on May 17th failed, so the Union troops decided to try and draw the Confederate forces by moving towards the south instead.
Lee had other ideas, however. Lee ordered Ewell to locate the northern part of the Union force and conduct a reconnaissance. A majority of Ewell’s troops travelled with him towards Harris farm where they encountered several heavy artillery soldiers that were undertaking infantry duty. Fighting lasted for several hours until Lee recalled his men. The advance of Union forces to the south was delayed by the skirmish at Harris farm, so Grant’s intended plan of drawing Lee’s troops to more favorable ground was not placed into action until the evening of May 20th.
http://totallyhistory.com/battle-of-spotsylvania-court-house/
D Wednesday, May 18, 1864: Skirmish at Woodlands, Georgia. Situated directly in the path of Sherman's advance, the Barnsley Gardens and Resort estate witnesses a battle on May 18, 1864 and suffers irreparably during occupation of troops commanded by U.S. Gen. James McPherson.
http://www.barnsleyresort.com/history.aspx
D+ Wednesday, May 18, 1864: Skirmish at Woodlands (Barnsley Gardens and Resort), Georgia
http://blueandgraytrail.com/year/186405
FYI CSM Charles Hayden SGT Tiffanie G. SGT Mary G.CPL Ronald Keyes Jr SPC Michael Duricko, Ph.D MAJ Roland McDonald SSG Franklin BriantCPO William Glen (W.G.) Powell1stSgt Eugene Harless PO3 (Join to see)MSG Greg KellyMSG Joseph ChristofaroLTC Greg Henning CPT (Join to see) SGT John " Mac " McConnell LTC John Griscom LTC Thomas Tennant MAJ Robert (Bob) Petrarca SFC George Smith SPC Michael Terrell

LTC Stephen F. this is my choice. 1862: Vicksburg, Mississippi. Initial efforts by Union land and naval forces to capture Vicksburg and open the great waterway to navigation ended in failure. The first threat developed when Flag Officer David Glasgow Farragut West Gulf Blockading Squadron

Union General Ulysses S. Grant’s Army of Tennessee surrounds Vicksburg, you keep forcing me to show my 'Western' sympathies and Iowa heritage.

One little know fact is that on May 22, 1863, month and half before the Union victory, the 22nd Iowa Volunteer Infantry Regiment, with close support from the 21st Iowa Volunteer Infantry Regiment, the 11th Wisconsin Volunteer Infantry Regiment and the 77th Illinois Volunteer Infantry Regiment, were able to breach the Vicksburg defense along the Railroad Redoubt created by artillery fire, and about a dozen members of the 22nd Iowa entered the defenses at that point. The survivors from that group occupied a forward portion of the position for some hours. The breach was not successfully reinforced, and the attackers not killed or wounded, along with members of supporting units, were forced back as darkness fell. No one can actually say what might have happened if the Union had been able to reinforce and exploit the breach but Grant was aware of what another attack would cost in lives.

The following report is of 22nd Iowa Adjutant concerning the frontal assault of the Railroad Redoubt, on the morning of May 22, 1863:

"The enemy were on the alert and, as our colors rose above the crest of the hill, a thousand bayonets glistened in the sunlight above the parapet at Fort Beauregard. The strong work against which the main attack was directed covered about half an acre of ground, the walls being about fifteen feet high, surrounded by a ditch ten feet wide. A line of rifle pits connected it with others of the same kind, each of which was so arranged as to enfilade the approach to the other. The regiment succeeded in reaching—under a concentrated fire of grape and musketry—an almost impenetrable abatis, forty yards from the works, where it became necessary to reform the line, the men having become separated in crossing the obstructions. They promptly rallied to the flag and were again led to the charge. A few officers and about fifty men, succeeded in reaching the ditch surrounding the fort, but, having no scaling ladders, they were unable to enter the works. Sergeant Joseph E. Griffith of the 22nd, with some fifteen or twenty men, succeeded—by raising one another up the wall—in gaining an entrance and capturing a number of prisoners, but the fire from the enemy's rifle pits in rear of the fort, and the lack of reinforcements coming to their aid, rendered the place untenable. Sergeant Griffith and David Trine, of Company I, were the only survivors of this daring exploit."

Only two men of the 22nd Iowa who entered the fort survived. This was the last frontal assault of Fort Beauregard ever attempted.

The 22nd Iowa’s losses at Railroad Redoubt were heavy. Of the 200 engaged in the assault, 42 were killed or died of their wounds, 128 wounded and 19 captured. Theirs was the highest toll suffered in any regiment of Grant’s army in the siege of Vicksburg.

In the end, the Confederate position held, bringing on the Siege of Vicksburg.