Now on the Vicksburg side of the river, Grant’s men marched toward their first objective, Port Gibson, situated roughly ten miles east of Bruinsburg, which commanded the local road network. The road over which the blue soldiers now marched led to the Shaifer House, roughly 1.5 miles from Port Gibson.

Confederate Brig. Gen. Martin E. Green was inspecting his picket line at the Shaifer House shortly after midnight when he was amused to see Mrs. Shaifer and the women of the house frantically loading a wagon with all their household items. The general tried to calm their fears by telling them that the enemy could not possibly arrive before daylight. Just then, a single shot rang out as the Confederate pickets spotted movement in the distance. The stillness of the night was shattered as a volley of musketry came in reply. 

Green quickly mounted and raced back to Magnolia Church to alert his brigade. Fighting in the scattered fields and forest around the Shaifer House intensified as more Union regiments and batteries came into action. Almost by mutual consent, the fighting ebbed by 3:00 a.m., and the weary soldiers in blue and gray rested on their arms.

At dawn the battle was renewed in fury as Maj. Gen. John A. McClernand threw most of his XIII Corps toward Green’s thin gray line. Green called for reinforcements from Brig. Gen. Edward Tracy, who anchored the Confederate right flank roughly a mile and half to the northwest. Tracy dispatched infantry and artillery to Green’s assistance minutes before cannons began to pound his own line, signaling the advance of a new Union column under Brig. Gen. Peter Osterhaus. 

Despite the reinforcements, Green was still heavily outnumbered, and at around 10:00 a.m., his line collapsed. As Green’s men scrambled to the rear, Brig. Gen. John Bowen, in overall Confederate command on the field, worked feverishly to restore his line. The brigades of Brig. Gen. William Baldwin, just arriving from Vicksburg, and Col. Francis Cockrell’s from Grand Gulf, were placed into position astride the road at White and Irwin’s Branches of Willow Creek, a mile and a half east of Magnolia Church.

The Confederate right did not last long. The Union troops pushed forward all along the line, and fierce fighting continued throughout the afternoon. A desperate Confederate counterattack by Cockrell’s Missourians was repulsed, and Bowen ordered a retreat. The remaining garrison at Grand Gulf was evacuated the next day. The Battle of Port Gibson was a resounding Union victory that secured Grant’s beachhead east of the Mississippi River and cleared the way to the Southern Railroad supplying Vicksburg.

https://www.battlefields.org/learn/civil-war/battles/port-gibson