- Jul 1 1st public schoolhouse opens at Washington and Mason St, San Francisco
- Jul 1 US War Department decrees that Kansas and Tennessee are to be canvassed for volunteers
- Jul 2 Battle of Hoke's Run, West Virginia - small Union victory
- Jul 3 Colonel Jackson receives his commission as brigadier general
- Jul 3 Martinsburg, Virginia - Confederate forces pull out before US advance
Pony Express
Jul 3 Pony Express arrives in San Francisco with overland letters from NY
- Jul 4 In a special session of 27th Congress Lincoln requests 400,000 troops
- Jul 4 Skirmish at Harper's Ferry, West Virginia
- Jul 5 Battle of Carthage, Missouri - US General Sigel attacks pro-secessionist
- Jul 7 Battle of Laurel Hill, Virginia
- Jul 8 Confederate General Sibley is given command of rebel troops in New Mexico territory
- Jul 10 Lincoln writes to Kentucky's militia and says Union troops will not enter that state
- Jul 11 Battle of Laurel Mountain Virginia - General Morris forces retreat of rebels
- Jul 11 Battle of Rich Mountain, Virginia - Rosecrans forces rebels to surrender
Wild Bill Hickok
Jul 12 "Wild Bill" Hickok legend is born as he reputedly shoots and kills David McCanles in Rock Creek, Nebraska Territory; Hickok later acquitted of murder as court finds he acted in self defense.
- Jul 13 Battle of Corrick's Ford, Virginia (Carrick's Ford) - Union army takes total control of western Virginia
- Jul 14 General McDowell advances toward Fairfax Courthouse, Virginia with 40,000 troops
- Jul 14 Naval Engagement at Wilmington North Carolina - USS Daylight establishes blockade
- Jul 16 Manassas Campaign [->JUL 22]
- Jul 17 At Manassas, Virginia General Beauregard requests reinforcements for his 22,000 men, General Johnston is ordered to Manassas
- Jul 17 US Congress authorizes paper money
- Jul 18 Battle of Blackburn's Ford, Virginia
- Jul 20 Confederate states' congress began holding sessions in Richmond, Virginia
- Jul 21 First Battle of Bull Run [Battle of First Manassas], the first major battle of the US Civil War is fought near Manassas, Virginia and ends in a Confederate victory
- Jul 25 Skirmish at Fort Fillmore, New Mexico Territory - Rebels attack Union troops
- Jul 25 Washington, D.C. - Crittenden resolution is passed stating that the war is to be fought to preserve union and uphold the Constitution, not to alter slavery
- Jul 27 Battle of Mathias Point, Virginia - Rebel forces repel a Federal landing
- Jul 27 Battle of St Augustine Springs, New Mexico Territory
- Jul 27 Confederate troops occupy Fort Fillmore, New Mexico
George McClellan Takes Command
Jul 27 Union General George McClellan takes command from McDowell of Potomac Army
- Jul 31 Cherrapunji, located in Assam, India, receives 9,300 mm of rainfall in July, setting a world record