By 2 November 1862, Union forces controlled the Mississippi River and used the Mississippi tributaries to transport men and weapons, enabling them to win a series of victories in the west. . Despite repeated Union efforts, however, the stretch around Vicksburg remained firmly in Confederate hands. On 3 November, Ulysses S. Grant began moving his men along the Mississippi east bank to reach, and capture, Vicksburg. Hampered by bayous, swamps, mosquitoes and snakes, his army made slow progress. Meanwhile, William Sherman, a Union General, led a second advance towards the Chickasaw Bayou crossings. Grant and Sherman were both repulsed by Confederate forces led by General van Dorn, who also cut off the Union supply lines at Holly Springs. The Union forces were unsuccessful in further assaults in January 1863, but succeeded in taking the Arkansas Post (on a Mississippi tributary) on 9–11 January.