Minor battles occurred, which were notable for their effects on military and political actions and leadership appointments in the nascent war.

Although involving larger forces and Stuart's ambitious use of artillery, as well as noteworthy incidents and more apparent later effects on operations and the advancement of commanders, the September 11 action at Lewinsville was similar in the level of combat as in several other small battles, skirmishes, raids and reconnaissances of the two armies in northern Virginia in the fall of 1861.

[16] On July 27, 1861, President Abraham Lincoln appointed Major General George B. McClellan as commander of the Military Division of the Potomac, the main Union force responsible for the defense of Washington.

[18] After being called to Washington in July and through most of August, McClellan spent his time reorganizing and training the army and planning and supervising the enhancement and construction of fortifications and outposts in northern Virginia for the defense of Washington, D.C.[8][19] On August 14, when the 79th New York Infantry Regiment, as well as part of the 2nd Maine Infantry Regiment, mutinied over term of service, pay and other organizational issues, McClellan sent an artillery battery, two companies of cavalry and several companies of Regular Army infantry to suppress the mutiny.

[21][22] During the last week of August, unauthorized but successful Union reconnaissances and minor skirmishes occurred near Munson's Hill.

[23] The good performances by Union troops encouraged McClellan to plan and to oversee preparations for the reconnaissance by Brigadier General William F. Smith's brigade, including the 79th New York Infantry Regiment, toward Lewinsville on September 11.

[23] On September 11, 1861, a Union reconnaissance in force of about 1,800 soldiers moved at about 7:30 a.m. from their base camp in Virginia just across the Chain Bridge over the Potomac River to Lewinsville, Virginia, about four to five miles distance, arriving about 10:00 a.m.[25][26][27] The U.S. force was under the command of Colonel Isaac Stevens, with the artillery under the command of Captain Charles Griffin.

One of the scouts, Private John S. Mosby, the future "Gray Ghost", saw a "gaily dressed" Union colonel on a splendid horse and took aim at him with a carbine.

Elliot's company of the 79th New York Infantry Regiment, who covered the withdrawal from the surprise rifle fire of Stuart's hidden skirmishers.

[34][35][36] The Confederate forces stayed in the woods during most of the conflict so as not to openly expose their positions, which they changed occasionally.

[4][26][44][45][46] Most of the artillery shells of both armies, nearly all from distances almost 2,800 yards apart, sailed over the heads of their targets, resulting in the light casualties.

After allowing the 19th Indiana Infantry Regiment skirmishers to pass through, Poe set up artillery for use against the Confederate cavalry still in view.

[49] Even McClellan came forward about one-half hour later and after calming down about an engagement possibly having occurred, congratulated Smith, but not Stevens, and visited with the wounded before departing.

"[14] At least three slightly different versions of a story about Poe leaving a note inviting Stuart, whom he had known from their time at West Point two classes apart, at Willard's hotel in Washington D.C. can be found in the sources.

"[42] McClellan's report to Union General-in-chief Winfield Scott that the men "behaved most admirably under fire" and that "We shall have no more Bull Run affairs".

[20][53] Confederate Colonel J. E. B. Stuart, later major general and commander of the cavalry in the Army of Northern Virginia, received special praise for his role in the battle and his proficiency and zeal in the discharge of his duties from General Longstreet, Stuart's immediate commanding officer.

[61][62] Orlando Poe became chief engineer for Major General William T. Sherman from December 1863 until the end of the war.

[67] This setback made McClellan even more determined to avoid any potentially risky operations without careful planning and preparation.

[69] The Confederates stayed at Centreville, Fairfax Court House and other camps in northern Virginia in the Washington, D.C. vicinity until then.

McClellan's time and energy became further spread out when he was named General-in-chief to replace the retiring Lieutenant General Winfield Scott on November 1, 1861, a position which he held until March 12, 1862.

[72] Union troops began to move slowly toward Manassas on March 7 while Johnston started to pull back from more advanced positions in response.

[74][75] Union troops found burning material and damaged railroad installations with little of value left at Manassas on the same day.

[79] On March 17, Union forces finally began to move by boat toward Fort Monroe for the start of the Peninsula Campaign.