Notified of the threat, Pemberton dispatched Maj. Gen. W. W. Loring’s Division to halt the Union advance. Fort Pemberton, overlooking the Yalabusha River 90 miles north of Vicksburg, was quickly constructed of earth and cotton bales. The land surrounding the fort was completely flooded, permitting approach by water only. On March 11, the Union gunboats began an artillery bombardment and were promptly greeted by a heavy return fire as “Old Blizzards” Loring gained his nickname by pacing the parapet and urging his gunners to, “Give them blizzards, boys! Give them blizzards!” Grant had planned to send 30,000 men through the Yazoo Pass; but Loring’s gunners blasted back every attempt to pass the fort, forcing the fleet to withdraw. The Yazoo Pass expedition was one of the great flanking attempts of the war—the route from Milliken’s Bend to the rear of Vicksburg through the pass was over 700 miles, yet it was only 30 miles direct from Milliken’s Bend to Vicksburg. THE STEELE’S BAYOU EXPEDITION. The last and most extraordinary of Grant’s unsuccessful attempts to reach Vicksburg was the Steele’s Bayou expedition through 200 miles of narrow, twisting bayous north of Vicksburg. Like the Yazoo Pass operation, it was an effort to turn the city’s right flank. This shorter route had been originally scouted in order to send aid to the Yazoo Pass expedition when that column seemed in great danger of being cut off and captured. Further exploration suggested the route to the bluffs by way of Steele’s Bayou might prove the best of all possible approaches to Vicksburg, and Porter himself commanded the squadron of 11 vessels which entered Steele’s Bayou from the Yazoo River on March 16. The route was heavily obstructed by natural hazards, but Porter, warned by apprehensive officers who feared that superstructures would be carried away in crashing through the closely overhung waterways, answered with the declaration, “All I need is an engine, guns, and a hull to float them.” Progress was slow through winding streams barely wide enough to admit passage of the gunboats. This time alert Confederates, aided by treacherous obstructions in the mouth of the Rolling Fork, nearly succeeded in shutting up and capturing the entire fleet by felling huge trees across the bayou to block Porter’s retreat. [Illustration: _Skirmishing in the heavily wooded and flooded bottom lands during the bayou expeditions._ From a wartime sketch.]