Grant's Canal (also known as Williams's Canal) was an attempted military-use canal through De Soto Point in Louisiana, across the Mississippi River from Vicksburg, Mississippi. During the American Civil War, Union Navy forces attempted to capture the city of Vicksburg in 1862, but were unable to do so with army support. Union Brigadier General Thomas Williams was sent to De Soto Point with 3,200 men to dig a canal capable of bypassing the strong Confederate defenses around Vicksburg. Despite help from local plantation slaves, disease and falling river levels prevented Williams from successfully constructing the canal, and the project was abandoned until January 1863, when Union Major General Ulysses S. Grant took an interest in the project.
Grant attempted to solve some of the issues inherent with the canal by moving the upstream entrance to a spot with a stronger current, but heavy rains and flooding that broke a dam prevented the project from succeeding. Grant eventually used other methods to capture Vicksburg, whose Confederate garrison surrendered on July 4, 1863. In 1876, the Mississippi River changed course to cut across De Soto Point, eventually isolating Vicksburg from the river, but the completion of the Yazoo Diversion Canal in 1903 restored Vicksburg's river access. Most of the canal site has since been destroyed by agriculture, but a small section survives. This section was donated by local landowners to the National Park Service and became part of Vicksburg National Military Park in 1990. A 1974 article in The Military Engineer calculated that the canal would likely have been successful if the dam at the downstream end of the canal had been opened.
During the opening days of the American Civil War in 1861, Winfield Scott, Commanding General of the United States Army developed the Anaconda Plan for defeating the Confederate States of America. A major part of this plan was controlling the Mississippi River. In early 1862, the Union Army defeated Confederate forces in a number of significant battles, including Shiloh, First Corinth, Fort Donelson, and Island Number Ten. The city of New Orleans, Louisiana, also fell to Union troops in late April. Between the capture of New Orleans and the battlefield victories, much of the Mississippi Valley was in Union hands. Flag Officer David Glasgow Farragut commanded the Union Navy elements that had been present at New Orleans, and took his ships upriver to the city of Vicksburg, Mississippi, which was considered to be strategically valuable. After reaching Vicksburg in mid-May, Farragut unsuccessfully demanded that the city surrender to his fleet. On May 20, the first Union shot towards Vicksburg was fired by USS Oneida, and more bombardments followed on May 26 and 28 before Farragut decided to fall back to New Orleans, a move that proved to be politically unpopular.Another attempt on the city would be made in June. While an infantry force under Union Brigadier General Thomas Williams had accompanied Farragut in May, this time Williams would bring a 3,200-man force, which was almost three times more men than he had previously had. Williams's infantrymen, Farragurt's navy ships, and a group of ships armed with mortars commanded by Commodore David Dixon Porter left the city of Baton Rouge, Louisiana, on June 20. Five days later, the Vicksburg area was reached. On June 26, Porter and Farragut's ships attempted to bombard the Confederate artillery batteries defending the city into submission, but were unable to do so. Two days later, Farragut ordered most of his ships (but not Porter's) to pass in front of the city's defenses to meet a fleet of Union ironclads that had traveled down the river from Memphis, Tennessee. Farragut's movement involved navigating around De Soto Point, a peninsula of land on the Louisiana side of the river, where the Mississippi River made a horseshoe-shaped meander. The Union ships suffered damage, but were able to pass the batteries. Both Farragut and the commander of the ironclads, Flag Officer Charles Davis agreed that the navy could not capture the city without large numbers of army troops and that the needed number of infantrymen would not be released by the Union high command for the Vicksburg operations.
After this determination, a canal that was being built across De Soto Point gained new importance. On June 27, Williams's men, as well as local plantation slaves who believed they would be freed for their work, had begun digging a canal across De Soto Point. However, Williams actually only intended of freeing them if the canal was completed successfully. As planned, the canal would have openings on the river 6 miles (9.7 km) above and 3.5 miles (5.6 km) below Vicksburg and had an intended width of 50 feet (15 m). If the plan worked as intended, the Mississippi would cut through the canal ditch, allowing Union ships to traverse the river without being fired on by the defenders of Vicksburg. It was also considered possible that the river would move from its old course through the canal cut, isolating Vicksburg from the river entirely. Around 1,200 to 1,500 African Americans worked on the project, but progress was hampered by the falling level of the river and outbreaks of disease. The temperature in the area sometimes reached as much as 110 °F (43 °C), potable water was scarce, and the mosquito-ridden swamps in the area led one Union doctor to state that the swamps contained "as much death to the square inch as would be possible for the laboratory of nature to compound". Malaria, dysentery, and scurvy were common among the workers, and supplies of the medicine quinine ran out. Disease was further promoted by soldiers dumping raw sewage into the Mississippi River, which was also their source of drinking water.The geology of the ground where the canal was dug was though to consist of about 11 feet (3.4 m) of clay with sand below. A river current would cut through the sand, but not the clay, it was thought, so the clay needed to be entirely removed before the canal was opened to the river. By July 4, 1862, the cut was only about 7 feet (2.1 m) deep. A week later, the depth of the canal was 1.5 feet (0.46 m) below the surface level of the river and on July 17 the canal had a depth of 13 feet (4.0 m) and a width of 18 feet (5.5 m), although the Mississippi River's level had fallen to below the trough of the canal. As the conditions deteriorated further, Williams decided that the canal was no longer feasible. His force had been reduced to 800 healthy men by disease, and Williams ordered his men from De Soto Point. The canal work ended on July 24. With the withdrawal of the infantrymen being at least part of his decision, Davis withdrew his ironclads upriver to Helena, Arkansas. When Confederate soldiers later examined the area where the canal construction had taken place, they found 600 graves and 500 abandoned African Americans. The canal had eventually reached a depth of 13 feet (4.0 m) was 18 feet (5.5 m) wide, but these dimensions were not enough to allow navigation.
Despite some urging from a Vicksburg newspaper editor, Confederate troops never filled in the traces of the canal. With the level of the Mississippi River rising in January 1863, Union Major General Ulysses S. Grant decided that the canal plan should be revisited. The steamboat Catahoula was sent to the area to scout the remains of the canal cut. Both the captain of the vessel and a newspaperman onboard reported that while there was water standing in the canal, it was stagnant and did not have a current and that the cut needed significant work before large ships such as the Union Navy ironclads could pass through it. After making some adjustments to the plans of the canal, Grant ordered that the digging resume. Visiting Union officers later found that the water was only 2 feet (0.61 m) in the ditch and also noted the lack of a current, although depths of up to 8 feet (2.4 m) and widths up to 12 feet (3.7 m) were also reported.The project had the support of President Abraham Lincoln and Captain F. E. Prime, an engineer, was tasked with overseeing the project. When the early attempts at working on the canal failed to achieve significant progress, Grant ordered that the upstream end of the canal be moved to a point that allowed for a stronger current to flow into the ditch. The canal was also widened, but because there was water in the canal, the newly-widen points only had a depth down to the water level. By the end of the month, Grant was beginning to think that the canal project would not succeed, but continue with the construction. Outbreaks of disease struck again, and the levees around the project frequently broke, flooding parts of the canal. The diggers were also exposed to Confederate artillery fire. By now, the construction had been divided into 160-foot (49 m) sections, with the intention of making each section 6 feet (1.8 m) deep and 60 feet (18 m) wide.In February, dredging boats were sent from Louisville, Kentucky, speeding the construction progress. However, rains hampered the project by exposing poorly-buried graves from the Battle of Chickasaw Bayou and turning the soil to a consistency Union Major General William T. Sherman described as "wet, almost water". Union newspapers criticized the project, and the Confederates built new artillery batteries capable of enfilading most of the canal. The dam holding the upstream end of the canal failed on March 7, inundating the canal. The breach in the dam could not be fixed, and the cut began to fill with sediment. Two large dredging boats, Hercules and Sampson, were sent to try to clear the channel, but they were driven off by Confederate artillery fire. The canal had reached a width of about 60 feet (18 m) and a depth of about 9 feet (2.7 m) to 12 feet (3.7 m). A 1974 article published in The Military Engineer calculated that if the dam at the downstream end of the canal had been opened along with the breach in the upper canal, then a current strong enough to successfully erode through the canal cut would have probably been produced. While Grant viewed the canal construction as a good way to prevent idleness among his soldiers, he eventually came up with another way to get troops past Vicksburg.
Grant decided to land troops on the Mississippi side of the river below Vicksburg in April. By mid-May, Grant's men had fought their way to Vicksburg, and placed it under siege. The siege of Vicksburg continued until the Confederate defenders surrendered on July 4. After Vicksburg surrendered, the Confederate garrison of Port Hudson, Louisiana, followed suit, giving the Union full control of the Mississippi River. In April 1876, the Mississippi River changed course, cutting through De Soto Point and eventually isolating Vicksburg from the riverfront after the oxbow lake formed by the course change became cut off from the river. Vicksburg would not be a river town again until the completion of the Yazoo Diversion Canal in 1903. While most of the canal path has since been destroyed by agriculture, a small section still remains. The owners of the tract donated it to the National Park Service and it was added to Vicksburg National Military Park in 1990. Also at the site is commemoration for the Union African American soldiers who fought at the battles of Milliken's Bend and Goodrich's Landing. A monument to the 9th Connecticut Infantry Regiment was also dedicated at the site in 2008. The National Park Service unit is located in Madison Parish, Louisiana.