Explanation: Maj. Gen. Thomas Jackson was ordered to conduct "diversionary" operations in the Shenandoah Valley to divert Union troops away from the planned Union offensive in Richmond, Va., and cause mass confusion with the Union army.
Maj. Gen. Thomas J. Jackson's Shenandoah Valley Campaign of 1862 is one of the most studied campaigns of military history. This campaign demonstrates how a numerically inferior force can defeat larger forces by fast movement, surprise attack, and intelligent use of the terrain. In March, as a Union force under Maj. Gen. Nathaniel Banks began to advance cautiously up the Shenandoah Valley, Jackson retreated to Mount Jackson where he could defend the Valley Turnpike. His task was two-fold, to prevent deep penetration into the Valley and to tie down as many Union forces as possible. When he learned that Banks was ready to detach part of his force to assist the Army of the Potomac then being concentrated on the Peninsula to threaten Richmond, Jackson marched down the Turnpike and fought a battle at Kernstown on March 23. Although defeated, Jackson's aggressive move convinced Washington that Confederate forces in the Valley posed a real threat to Washington, and Maj. Gen. George B. McClellan, with his army preparing to move on Richmond, was denied reinforcements at a critical moment in the Peninsular Campaign.
In late April, Jackson left part of his enlarged command under Maj. Gen. Richard S. Ewell to confront Banks and marched with about 9,000 men through Staunton to meet a second Union army under Maj. Gen. John C. Fremont, whose vanguard approached on the Parkersburg Road from western Virginia. Banks was convinced that Jackson was leaving the Valley to join the Confederate army at Richmond. But on May 8, Jackson turned up to defeat two brigades of Fremont's force, under Brig. Gens. Robert Milroy and Robert Schenck, at McDowell. He then marched swiftly back to unite with Ewell against Banks.
On May 23, Jackson overran a detached Union force at Front Royal and advanced toward Winchester, threatening to cut off the Union army that was concentrated around Strasburg. On May 24, after a running battle along the Valley Turnpike from Middletown to Newtown, Banks made a stand on the heights south of Winchester.
On May 25, Jackson attacked and overwhelmed the Union defenders, who broke and fled in a panic to the Potomac River. Banks was reinforced and again started up the Valley Turnpike, intending to link up with Brig. Gen. James Shields' Union division near Strasburg. Shields's division spearheaded the march of Maj. Gen. Irwin McDowell's corps recalled from Fredericksburg, while Fremont's army converged on Strasburg from the west. Jackson withdrew, narrowly avoiding being cut off from his line of retreat by these converging columns.
The Union armies now began a two-prong offensive against Jackson. Fremont's troops advanced up the Valley Turnpike while Shields's column marched up the Luray Road along the South Fork. At this point nearly 25,000 men were being brought to bear on Jackson's 17,000. Jackson's cavalry commander, Brig. Gen. Turner Ashby was killed while fighting a rear guard action near Harrisonburg on June 6.
Jackson concentrated his forces near the bridge at Port Republic, situating himself between the two Union columns that were separated by the mountain and the rain-swollen Shenandoah South Fork. On June 8, Fremont attacked Ewell's division at Cross Keys but was driven back. During this battle General Issac Trimble's brigade achieved great glory.
On June 9, Jackson with his remaining force attacked Shields east and north of Port Republic, while Ewell withdrew from Fremont's front burning the bridge behind him. Ewell joined with Jackson to defeat Shields. Both Union forces retreated, freeing Jackson's army to reinforce the Confederate army at Richmond.
In 5 weeks, Jackson's army had marched more than 650 miles and inflicted more than 7,000 Union casualties, at a cost of only 2,500 Confederates. More importantly, his campaign had tied up Union forces three times his strength. Jackson's victories infused new hope and enthusiasm for the Confederate cause, and materially contributed to the defeat of McClellan's Peninsula Campaign. Jackson maneuvered with great skill, made two and a hair round tripe up and down the valley in about 6 weeks, and defeated the superior Union forces in detail.
By June 9, 1862, Jackson had fought and won 5 battles—McDowell, Front Royal, Winchester, Cross Keys, and Port Republic.