In April, 1863 Major General Ulysses Grant decide to alter his Vicksburg strategy by moving his troops down the Mississippi River. On April 29, 1863 the Federals launched a determined assault on Grand Gulf. The Confederates made a rigorous reply to the Union attack with their eight heavy field pieces. For six and a half hours the two forts were shelled by the gunboats. Realizing how capable the Confederate batteries were at withstanding the assault, the gunboats were signaled to withdraw. General Grant, who witnessed the encounter on board a tug in the Mississippi River, decided against trying to run the unarmed transports, loaded to the gunwales with men, past the Confederate batteries. Instead, Grant executed his alternate plan of disembarking his men and marching them down the Louisiana side of the river to Disheroon's Plantation, about three miles down the river.