On April 30, 1863, Maj. Gen. Ulysses S. Grant's army crossed the Mississippi River at Bruinsburg, 30 miles downstream from the Confederate defenses of Vicksburg. Grant hoped to move east toward the capital at Jackson to block reinforcements and supplies from reaching the strategic river city. Port Gibson, ten miles east of Bruinsburg on the Little Bayou Pierre River, commanded the approach routes and was the first Federal objective. Fierce fighting erupted early on May 1 as the Union soldiers encountered Confederate defenders in the dense undergrowth shortly after midnight. The battle continued for most of the next day as successive Confederate lines buckled under the weight of the Union advances. A counterattack was repulsed in the late afternoon and the Southerners were forced from the field. The battle firmly secured a Union beachhead on the east bank of the Mississippi River and enabled Grant to push northeastward unopposed.