May 18, 1863:
The siege at Vicksburg commences.
Beginning in the winter of 1862-63, Grant made several attempts to capture Vicksburg. In March, he marched his army down the west bank of the Mississippi, while Union Admiral David Porter’s flotilla ran past the substantial batteries that protected the city.
They met south of the city, and Grant crossed the river and entered Mississippi. He then moved north to approach Vicksburg from its more lightly defended eastern side. In May, he had to split his army to deal with a threat from Joseph Johnston’s Rebels in Jackson, the state capital that lay 40 miles east of Vicksburg. After defeating Johnston’s forces, Grant moved toward Vicksburg.
On May 16, Grant fought the Confederates under John C. Pemberton at Champion Hill and defeated them decisively. He then attacked again at the Big Black River the next day, and Pemberton fled into Vicksburg with Grant following close behind. The trap was now complete and Pemberton was stuck in Vicksburg, although his forces would hold out until July 4.
In the three weeks since Grant crossed the Mississippi in the campaign to capture Vicksburg, his men marched 180 miles and won five battles. They took nearly 100 Confederate artillery pieces and nearly 6,000 prisoners, all with relatively light losses.
Taken from: https://www.history.com/this-day-in-history