The first Federal crossing of the Big Black River.The pursuit of Pemberton's army brought McClernand's Corps to the defenses of the Big Black River Bridge early on May 17, 1863. McPherson was close behind. McClernand's division carried the defenses and Bowen and Vaughn's men fled with precipitate haste over the dreary swamp to the river and crossed over and burned the railroad and other bridges just in time to prevent McClernand from following. The necessary delay was aggravating to Grant's forces. The rest of the day and night was consumed in building bridges. Sherman had the only pontoon-train with the army and his bridge was the first ready at Bridgeport, early in the evening.