John T. Hubbell, "McDowell, Irvin," American National Biography Online, February 2000, http://www.anb.org/articles/05/05-00503.html.
When the Civil War began, McDowell was a brevet major and again served on General Scott's staff. McDowell was a man of physical energy, wide interests, and strong opinions with no obvious vices and practically no personal charm or ordinary good manners. He had powerful patrons, especially Salmon P. Chase, but no observable qualifications for high command. In late May 1861 he was given the command of the Union forces in the Department of Northeastern Virginia with expectations of an early offensive. While McDowell took steps to organize his "army," the Confederates took up positions along Bull Run, about five miles north of Manassas, Virginia. Their commander was P.G.T. Beauregard, McDowell's classmate and the victor at Fort Sumter. Elements of both armies faced off near Winchester, the Confederates under Joseph E. Johnston and the Federals under Robert Patterson. In order to prevent Johnston from reinforcing Beauregard, Patterson should have attacked or at least pressed his opponent, or he might have marched his forces to support McDowell. He did neither, although Scott's orders clearly directed him to occupy Johnston. McDowell planned to outflank Beauregard and force him out of his fixed positions along Bull Run, a sensible enough plan, assuming energetic leadership, effective staff work, and experienced soldiers in the ranks. Also, Patterson would have to contain Johnston. These happy circumstances did not occur, and McDowell, for all his outward show of confidence, doubted that he could make the plan work, mainly because his soldiers were without experience or proper training.