First Battle of Kernstown. The Confederate attack was repulsed, but it still was considered concerning enough to return the rest of Banks's command to the Valley and to hold another corps at Manassas, Virginia, depriving McClellan's campaign of about 60,000 men. After Kernstown, Jackson withdrew south in the valley, where he joined forces with Major General Richard Ewell. Leaving Ewell and his men to face Banks, Jackson took his troops southwest towards McDowell, Virginia, in early May to confront a Union force commanded by Major General John C. Frémont. Part of Frémont's command led by Brigadier General Robert H. Milroy attacked Jackson's men on May 8 in the Battle of McDowell. The Confederates were victorious, and Frémont withdrew his force. Jackson then moved his men back north to face Banks. By then, part of Banks's force had again been transferred out of the Valley, and on May 12, the division of Brigadier General James Shields was ordered east. Banks then withdrew his remaining force to Strasburg. Jackson's approach Meanwhile, Ewell had received an order on May 17 dated May 13 from General Joseph E. Johnston to take his force from the Valley to support Johnston's army against McClellan. Jackson sent a message to Johnston that same day requesting that Ewell be allowed to remain with his command so that a blow could be struck against Banks, and on May 18 Jackson and Ewell decided that Ewell should remain under Jackson's authority until the reply from Johnston was received. As it took several days for communications to travel between Jackson and Johnston, Jackson did not receive a reply on May 20, when another set of orders for Ewell to move east were received. Jackson then contacted General Robert E. Lee, an advisor to Confederate President Jefferson Davis requesting the continued use of Ewell's men, but another message from Johnston arrived later that day giving Jackson discretionary use of Ewell's command. Between Jackson and Ewell's forces, the Confederates nominally had 17,000 men, although historian Gary Ecelbarger estimates that due to desertion and straggling the true number of effective was closer to 12,000 or 14,000. The Confederates resumed moving north to strike Banks. The Union forces at Strasburg had built fortifications facing south, but Jackson decided to move to the east and destroy the Union outpost at Front Royal. By taking Front Royal, Jackson could sever Banks's communications to the east and then