Bull Run
2 of the 7 encyclopedias on this shelf carry an entry for Bull Run. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
Battle of, the first battle of the Civil War. It occurred Sunday, July 21, 1861. The battlefield is in Virginia, about twenty-five miles west of Washington. The Confederate army under General Beauregard lay at Manassas in position to defend Richmond. The Federal troops under General McDowell advanced to attack them. About 28,000 troops were available on each side. At first victory seemed on the Union side. The Confederates thought they were defeated; but the Union troops lost courage just in time to save their opponents. Demoralization grew into panic; and a retreat, degenerating in many instances into every man for himself, ensued. The Federal army, accompanied by spectators, citizens, and even congressmen, rushed pell mell for the bridges that lead across the Potomac into Washington, and left the corpsestrewn battlefield to the Confederates. Supplies, guns, ammunition, wagons, everything that could be thrown away to lighten flight, was left by the wayside. Something less than 1,000 men were killed in the battle and nearly 3,000 were wounded. The Union loss was, of course, the heavier. At this date the retreat may seem ludicrous; but it was a serious affair at the time and showed that the war was to be no pretense. A second battle of Bull Run, sometimes called the battle of Manassas, was fought August 29-30, 1862, between the Confederate troops under Lee and the Federal forces under Pope. Lee's forces numbered about 54,000, Pope's 65,000. After two days of stubborn fighting the Federal troops were driven from the field, leaving 10,000 killed and wounded. The Confederate loss was almost as heavy. See Civil War 2026 Editor's Note: The detail that fixed this battle in memory: Washington society drove out with picnic baskets to watch, and was swept up in the rout — the "Great Skedaddle" back to the capital. Bull Run destroyed the illusion that the war would be short, and gave Thomas Jackson his name, when a fellow officer pointed and said he stood "like a stone wall." (Ed: BR 2026-06-24)
Collier's New Encyclopedia (1921)
or BULL'S RUN, a stream in Virginia, dividing Fairfax and Prince William counties, in the N. E. part of the State, and flowing into the Occoquan river 14 miles from the Potomac. On its banks were fought two of the most memorable battles during the Civil War. After a series of heavy skirmishes, July 16-19, 1861, the Union army under General McDowell was, on the 21st, utterly routed by the Confederates under the command of Generals Beauregard and J. E. Johnston. The Union loss was about 3,000 men, while that of the Confederates was estimated at nearly 2,000 men. The former lost, in addition, 27 guns, besides an immense quantity of small arms, ammunition, stores, provisions, and accouterments. On Aug. 30, 1862, another great battle was fought here between the Union forces commanded by General Pope, and the Confederates under Generals Lee, Longstreet, and "Stonewall" Jackson, when the former were again defeated with heavy loss. The three battles of Groveton, Bull's Run, and Chantilly, fought in three successive days, cost the Union cause about 20,000 men in killed, wounded, missing, and prisoners, 30 guns, and 30,000 small arms. The first battle of Bull Run is sometimes known as the battle of Manassas.