Following the unsuccessful 1st Vicksburg Campaign and the battle at Chickasaw Bayou/Bluffs, Maj. Gen. Ulysses S. Grant encouraged more waterborne offensives. In June 1862, Federals from Baton Rouge, Louisiana had traveled up the Mississippi River and begun doomed efforts to dig a canal through the Swampy Toe peninsula opposite vicksburg. Had the canal been completed, Union war vessels could have used this route to stay out of the range of Vicksburg's cannon. On January 22nd 1863, Grant set troops of Maj. Gen. John A. McClernand's command to work on a renewal of this project. A 2nd canal was begun shortly thereafter by Maj. Gen. William T. Sherman's men at Duckport, northwest of Vicksburg on the Mississippi River's west bank, its objective roughly the same as the first. The canal would link inland bayous and bring Union boats from Duckport to a point 20 miles south of Vicksburg.
Simultaneously with these projects, Maj. Gen. James B. McPherson led probes south from Lake Providence and Bayou Macon, Louisiana, looking for a bayou-and-lake route to Vicksburg's southern approaches. All these projects were to end late in March, prior to the 2nd Vicksburg Campaign.
The Yazoo Pass Expedition was also conceived in January. Lt. Col. of Engineers James. H. Wilson received orders on January 29th to bring men and equipment from Helena, Arkansas and open a levee sealing the Yazoo Pass, a natural inland water route connecting the Mississippi River and, moving east and south, Moon Lake and the Coldwater River. This passage would allow vessels to move from the Coldwater to the Tallahatchie and Yazoo rivers and permit the lengthy but safe passage of troops and gunboats to Vicksburg's northern approaches. Crossing from the Arkansas banks on February 2-3rd, Wilson had workmen cut into the levee, then blast a hole through. The natural flow of water enlarged the hole and allowed vessels to enter the pass by March 7th. Aware of the probability of this manuever, Lt. Gen. John C. Pemberton had ordered the pass blocked with obstructions before Wilson's project began. Subsequently, Wilson spent the 8-10th clearing enormous trees and stumps from the waterway.
Following behind were 5,000 Union troops, under Brig. Gen. Leonard F. Ross, aboard transports, the ironclads Chillicothe and Baron De Kalb, and several light combat vessels. A 22-boat flotilla, by March 10, it had passed all obstructions and travelled south on the Tallahatchie to that river's confluence with the Yalobusha. These were the headwaters of the Yazoo. At this point, the Tallahatchie flowed east, joined the yalobusha, then reached the Yazoo.
The neck of land between the Tallahatchie on the north and the Yazoo on the south was approximately 400 yards wide. Here, Confederates built small Fort Pemberton. Commanded by Maj. Gen. William Wing Loring and holding fewer than 10 cannon, not all of which could be brought to bear on the flotilla, the fort held off the Federals. Under naval Lt. Cmdr. Watson Smith, the Chillicothe and Baron De Kalb exchanged fire with the fort but, Wilson later claimed, would not come any closer than 800 yards to it. Swamp, bayou, and positioning did not allow an assault by Ross's troops. Wilson erected a land battery northeast of the fort on the 12-12th. Until the 20th, efforts were made at artillery assault and infantry probes. An encounter on the 16th disabled the Chillicothe.
After a final failure on the 20th, the flotilla put about and headed for Moon Lake, effectively ending the Yazoo Pass Expedition. Met on the waterway on the 21st by Union reinforcements under Brig. Gen. Isaac F. Quinby, Ross was persuaded to return to Fort Pemberton. Two more unsuccessful artillery duels were fought on April 1st and 3rd. During this period, Rear Adm. David D. Porter tried a 2nd water route on his Steele's Bayou Expedition.