Yazoo Pass Expedition The Yazoo Pass Expedition was a joint operation of Major General Ulysses S . Grant ' s Army of the Tennessee and Rear Admiral David D . Porter ' s Mississippi River Squadron in the Vicksburg Campaign of the American Civil War . Grant ' s objective was to get his troops into a flanking position against the Rebel defenders . The expedition was an effort to bypass the Confederate defenses on the bluffs near the city by using the backwaters of the Mississippi Delta as a route from the Mississippi River to the Yazoo River . Once on the Yazoo , the Army would be able to cross the river unopposed and thus achieve their goal . The operation would require a deep penetration into enemy territory that was dominated by water , so cooperation between the two services was necessary . The Army was led by Brigadier General Leonard F . Ross . Naval commander was Lieutenant Commander Watson Smith , who was in extremely poor health ; his health was an important factor in the ultimate failure of the expedition . The expedition began on February 3 , 1863 with the breaching of a levee on the Mississippi River , allowing water to flow from the river into a former channel that connected with the Yazoo River through a series of other waterways . The attacking fleet passed through the cut into Moon Lake , through the Yazoo Pass to the Coldwater River , and then into the Tallahatchie , which combines with the Yalobusha to form the Yazoo River , which met the Mississippi a short distance above Vicksburg . From the start , the expedition was delayed by natural obstacles that were more serious than the perfunctory Confederate resistance , so forward motion was as little as ten miles ( 16 km ) a day . Because progress was so slow , the Confederate Army under Lieutenant General John C . Pemberton was able to set up a fort and block passage of the Federal fleet near the town of Greenwood , Mississippi . The Federal fleet did not approach the fort until March 11 ; then , the ironclad gunboats of the fleet were repulsed in a series of gunfire exchanges on three separate days . The Army troops present could not contribute significantly to the battle because of the nature of the ground , much of which was under water . Following the third repulse on March 16 , Lieutenant Commander Smith ' s health failed him completely , and he turned command over to Lieutenant Commander James P . Foster . Foster and Ross decided to withdraw to the Mississippi . They were temporarily persuaded to try again when they met reinforcements for the Army , but they resumed their retreat when the new army commander , Brigadier General Isaac F . Quinby , saw the futility of further attacks . The entire force had returned by April 12 , and the expedition was over . Background . The Vicksburg Campaign was bogged down in early 1863 , following the repulse of the Union forces under Brigadier General William T . Sherman at Walnut Hills ( or Chickasaw Bayou ) late the previous year . Major General Ulysses S . Grant wanted to keep his troops busy until he could begin active campaigning later in the spring , so he ordered them to undertake several moves that would give the appearance of activity but would not bring on a major battle . Grant , writing in his memoirs long after the event , stated that he did not have great confidence that any of them would prove successful , although he was prepared to take advantage of them if they did . One of the operations he put in motion became known as the Yazoo Pass Expedition because it used a waterway of that name . Geography . The western part of the state of Mississippi , from the Tennessee state line to the north and Vicksburg at the south , is a part of the flood plain of the Mississippi River . As such , it is quite low ; in many places , it is in fact lower than the level of the river . The region is therefore occupied by numerous marshes , brakes , sloughs , bayous , lakes , creeks , and rivers that in the geologic past were parts of the river bed . Until the middle of the nineteenth century , overflow from the Mississippi continued to pass into these waters , and they could be used as alternatives to the main river for water transportation . One such route left the Mississippi at a point a little south of Helena , Arkansas , passed through Moon Lake ( an oxbow lake , i . e . a former loop of the river that had been cut off when it changed course ) , and followed the Yazoo Pass to the Coldwater River . The Coldwater is a tributary of the Tallahatchie River , which combines with the Yalobusha to form the Yazoo River at Greenwood , Mississippi . The Yazoo then flows 188 miles ( 303 km ) , to reenter the Mississippi a short distance above Vicksburg . This changed in 1856 , however , when the coming of the railroad induced the state to drain some of the land for agricultural uses . To that end , they built artificial levees to confine the river to its main course . Deprived of its principal source , the water level behind the levee dropped as much as eight feet ( approximately 2 . 5 m ) . Preliminaries . The Army and Navy had distinct but not incompatible reasons to get their forces to the east of Vicksburg . Grant wanted to get his soldiers onto dry ground with no rivers between him and the Confederate defense . Once that was done , he believed that he could flank Pemberton ' s Confederate army . At the same time , he could divert a part of the expedition up the Yalobusha River to destroy a railroad bridge that was enabling the enemy to threaten his own line of communications . Porter ' s purpose was to use his armored gunboats to destroy Rebel shipping at Yazoo City . He emphasized that any enemy ironclads must be destroyed , if possible on the stocks . Although the two services had divergent goals , this did not affect the expedition adversely ; its ultimate failure is ascribed to other causes . A preliminary survey by Acting Master George W . Brown in the tinclad confirmed the feasibility of the operation , and on February 3 , 1863 a group of some 400 pioneers under Lieutenant Colonel James H . Wilson dug two gaps in the levee at the site where the Old Yazoo Pass had formerly met the Mississippi . At this time , the difference in water level between the river and the former stream bed was eight feet ( 2 . 5 m ) , so the water rushed through the openings with great vigor , enlarging the gap and carrying away everything in its path . By the next day , the gap had increased in size to 80 yards ( 73 m ) . The flow was so great that the vessels assigned to the expedition could not safely enter for several days . The flotilla of gunboats and army transports passed through the gap on February 24 and immediately proceeded into Moon Lake . Advance and Confederate response . The naval contingent consisted of seven gunboats and a tug . Five of the gunboats were of a type known colloquially as " tinclads , " vessels of light draft carrying thin armor capable of protection only against infantry weapons : , , , , and . The other two were the larger and heavier , one of the original City class ironclad s , and , an inferior second - generation copy . Later , another gunboat , , and two rams , and , would join the expedition . Lieutenant Commander Watson Smith led the flotilla from his flagship " Rattler . " The Army contributed nine infantry regiments that were carried in thirteen transports . An additional 600 or so soldiers were sent aboard the tinclads to defend them , if necessary , from Rebel boarding parties that could be expected in an operation so deep in enemy territory . Grant would have sent more troops , but a shortage of available transports prevented him from doing so . The troops were a part of the XIII Corps , under the command of Brigadier General Leonard F . Ross . Later , they would be reinforced by a column led by Brigadier General Isaac F . Quinby , who ranked Ross . The Confederates in the meantime were not idle . Lieutenant General John C . Pemberton was aware of his opponents ' intent as soon as the levee had been breached , if not before , and he gave orders to Major General William W . Loring to stop them . He immediately organized some work details to block the Yazoo Pass and Coldwater River by felling trees across the streams , but they were largely ineffective . The obstructions were quickly removed by Union army engineers under the leadership of Lieutenant Colonel Wilson . More serious , however , was a fort that Loring ordered to be built a few miles upstream from the point where the Tallahatchie and Yalobusha Rivers combine to form the Yazoo . A peculiarity of the courses of the Tallahatchie and the Yazoo is that they flow past each other on opposite sides of a neck of land that is only a couple of hundred yards ( or meters ) wide . Here , Loring ' s men made a barricade of cotton bales , covered them with layers of dirt , and mounted a pair of heavy guns . This hastily - constructed earthwork was named " Fort Pemberton , " or sometimes " Fort Greenwood . " He had other batteries lining the bank of the Tallahatchie almost all the way to the Yalobusha , and still others on the Yazoo . In addition , he had built a boom or raft that could be swung out to block the stream , and in the channel just downstream of this he scuttled a ship , the former " Star of the West " . Loring had time to set up the defense because the progress of the Union flotilla was painfully slow . Instead of pushing ahead with his ironclads , Lieutenant Commander Smith insisted that the entire force , gunboats and transports alike , should move together . They could move only in daylight hours , but Smith continued to recoal his vessels during the day . Furthermore , they would waste hours in the early mornings and would stop at midday for lunch . Moving faster than the current , according to Smith , " brings us foul . " Ross protested strongly against the lack of urgency , as did Smith ' s second in command , Lieutenant Commander James P . Foster . Their pleas were disregarded . Smith ' s torpor may have been a result of his declining health ; he had been sick when the expedition started , but he had stayed on , hoping that he would improve when his fleet was in motion . Instead , he only got worse , and he eventually had to relinquish command to Foster . By then , however , it was too late . Clash at Fort Pemberton . The Union flotilla finally arrived in the vicinity of Fort Pemberton on March 11 , more than five weeks after the levee at Yazoo Cut had been breached . A probe sent out by the Army , accompanied by " Chillicothe , " found that the terrain near the fort was too marshy to support an attack by infantry . The attack would have to be carried out by the gunboats , aided by whatever artillery could be brought ashore and brought to bear . Not even all of the gunboats could participate ; because the river was rather narrow , only two boats could engage at a time , and these only bows on to the enemy . The initial probe was followed by a more determined bombardment by " Chillicothe " and " Baron De Kalb " . In this action , " Chillicothe " sustained the most serious injury of the operation . A shell from Fort Pemberton passed through one of her gun ports while the 11 - inch ( 280 mm ) gun was being loaded , striking the shell and causing both to explode . The gun itself was not harmed , but 14 members of the gun crew were killed or wounded . Another man was killed by a later hit . " Baron De Kalb " did not suffer any significant damage , because of her superior construction and because the Confederate gun crews concentrated their fire on the more vulnerable " Chillicothe . " The next day ( March 12 ) was given over to repairing the damage suffered by the gunboats , and giving them additional protection by placing cotton bales on the foredecks . Smith also landed a pair of 30 - pounder Parrott guns , one from his flagship " Rattler " and the other from " Forest Rose . " He also sent ashore a 12 - pounder howitzer . They were sited some 800 yards ( 730 m ) from the fort , and were , like the guns in the fort , shielded by cotton bales covered with dirt . The two ironclads returned to action on March 13 , this time assisted by the shore battery and the mortar boat . The Confederate gunners again concentrated their fire on " Chillicothe . " Although she lost only three wounded among her crew , the pounding she took from the enemy artillery loosened many of her armor plates and generally revealed the inadequacy of her construction . " Baron De Kalb , " although not punished so severely , lost three of her officers and men killed and three others wounded . The Rebels lost some of their men also , when a shell entered a magazine . Although it did not explode , its fuze set fire to the ammunition stored there , and the fire killed one man and burned 15 others . Another shell killed a man and wounded two others . At the end of the day , Fort Pemberton was basically unscathed ; the gunboats , however , particularly " Chillicothe , " had been badly battered . Smith failed to note that the Confederate fire was slackening at the end of the day , their ammunition supply being depleted . Smith spent the next two days repairing his vessels and landing a broadside 8 - inch ( 210 mm ) gun taken from " Baron De Kalb . " He and Ross decided to make a determined assault on Monday , March 16 . The ironclads would be pushed closer to Fort Pemberton than before in order to be better able to silence its guns . They would advance side by side with the mortar boat lashed between them . Infantry would follow in tinclads behind them , ready to go ashore as soon as the guns in the fort were knocked out and a suitable landing place could be found . The planned attack collapsed almost immediately when a series of shot or shell hit " Chillicothe ' s " casemate . The impact buckled the armor plates in such a manner that the gun port stoppers could not be raised . " Chillicothe " was forced to retire , and Smith decided to pull the relatively undamaged " Baron De Kalb " out of action also . That was essentially the end of the Union effort . Smith finally realized that his health was impeding the expedition , so he turned command over to his second - in - command , Lieutenant Commander James P . Foster . Foster and Ross decided together that further effort would be futile , so the flotilla began to withdraw the next day . They had not gone far when they encountered a group of Union transports bringing in reinforcements under the command of Brigadier General Isaac F . Quinby , whose appointment predated that of Ross and who therefore ranked him . Quinby ordered Ross to go back down the river to renew the attack , and he persuaded Foster ( whom he could not order ) to accompany him . A few desultory probes were launched in the next several days , but Quinby found what Ross already knew , that the land was unsuitable for an infantry assault . Quinby received orders from Grant to return to the Mississippi , where he and Ross were needed for the next assault on Vicksburg . The flotilla withdrew from Fort Pemberton for the last time , and by April 14 all had returned .