Gen. Jackson's force of 'foot cavalry', so called because they had marched 350 miles up and down the Shenandoah Valley and won 3 battles in 5 weeks, were in a race with 2 closing Union forces under John C Frémont and James Shields. Although each was numerically inferior to Jackson's force, together they would outnumber him but the 2 columns were separated by the Massanutten Moutain ridge and the south fork of the Shenandoah. Jackson held the only bridge at Port Republic so he decided to destroy them in detail. Richard S Ewell's division dug in at Cross Keys, 3 miles north west of the bridge to delay Frémont while Jackson dealt with Shields.
Although outnumbered considerably by Frémont's bluecoats, Ewell's men defended well, and the Union attacks were uncoordinated, and thrown back. Ewell was therefore requested to leave a holding force only, and send men to reinforce Port Republic

American Union Forces

Number engaged :

11,000

Casualties :

625 (5.68%)

American Confederate Forces

Number engaged :

6,000

Casualties :

272 (4.53%)