On Thursday, July 25, 1861, several changes occurred in the wake of the Battle of Bull Run.
Union General George McClellan arrived in Washington to replace Irvin McDowell. A general order was issued outlining the extent of his new command. General William Rosecrans replaced McClellan as commander of the Department of the Ohio and the "Army of Occupation, Western Virginia."
Nathaniel Banks replaced Robert Patterson as commander of the Army of the Shenandoah. Patterson, 69, had done a poor job of containing General Joseph E. Johnston's army in the Shenandoah Valley, allowing the Confederates to join with Beauregard at Bull Run. Patterson was relieved of command and given an honorable discharge, ending his service in the Civil War.
General John Frémont finally arrived in St. Louis to take over the newly created Department of the West. Frémont had been named to the command on July 3, and had spent much of the intervening time in New York trying to buy weapons and supplies.
Union General Jacob Cox, commanding the Kanawha Brigade of the Department of the Ohio, got behind Henry Wise's position at Tyler Mountain on July 24, forcing Wise to retreat to Charleston, Virginia (now West Virginia). As Cox approached the town, Wise retreated again. The Federals occupied the town on July 25.
The U.S. Senate passed the Crittenden-Johnson Resolution by a vote of 30-to-5. The House had previously approved the measure on July 22. The resolution stated that the war was being fought "to defend and maintain the supremacy of the Constitution and to preserve the Union" and not for "overthrowing or interfering with the rights or established institutions of those States." The measure was seen as necessary for keeping the slave states of Kentucky, Missouri and Maryland in the Union, but in a couple of weeks Lincoln would sign a confiscation act allowing for the seizure of property, including slaves, from rebellious citizens.
Robert M. T. Hunter replaced Robert Toombs as the Confederate Secretary of State. Toombs, the only member of Jefferson Davis's cabinet to voice opposition to the attack on Fort Sumter, had resigned to join the Confederate army. He received a commission as a brigadier general on July 19, and served as a brigade commander in Joe Johnston's Confederate Army of the Potomac.
At Mesilla, in New Mexico Territory, the Union garrison at Fort Fillmore attacked John Baylor's Confederates in a brief skirmish. The Union assault was repulsed and they eventually retreated back to the fort. When Baylor moved on the fort the following day, the Union troops abandoned it and retreated toward Fort Stanton. Baylor pursued, capturing stragglers by the dozens before overtaking the Federals and forcing their surrender at San Augustine Springs on July 27.