Believing that a frontal attack across the Monocacy would be too costly, Early sent Brig. Gen. John McCausland's cavalry of about 1,100 men down Buckeystown Road to find a ford and outflank the Union line. McCausland crossed the Monocacy below the McKinney-Worthington ford, about a mile downstream from the Georgetown Pike bridge, and attacked Wallace's left flank. Due to the rolling terrain, McCausland's men did not notice that four regiments of Ricketts's veteran troops had taken a position along a fence separating the Worthington and Thomas farms. Consequently, the Union line was able to fire a single volley that destroyed McCausland's front line and panicked the remaining Confederates. McCausland rallied his brigade and launched another attack, but was unable to break the Union line and retreated.