Joining a brigade of Louisiana regiments, it fought in Jackson's Valley campaign and at Gaines' Mill, Malvern Hill, Second Bull Run, Antietam, and Fredericksburg in 1862.

[2] On 24 June 1862, Nicholls was named colonel of the 15th Louisiana Infantry Regiment and promoted brigadier general on 14 October 1862.

[1] When the retreating Union force set the railroad bridge in fire, Colonel Kelly led his men across it.

Reaching a second stream spanned by a burning wagon bridge, Kelly led a group of soldiers across a ford then ordered his men to put out the flames, which they did.

Some of the regiment's soldiers were captured by Union troops on 30 May while guarding supplies at Front Royal, Virginia.

The Louisianans overran a Union artillery battery, were driven back, and recaptured the guns in a second charge.

[11] At the Second Battle of Bull Run on 28–30 August, the brigade was led by Colonel Henry Forno and consisted of the 5th, 6th, 7th, 8th, and 14th Louisiana Infantry Regiments.

[12] On 29 August at 5:30 pm, the 8th Louisiana Infantry joined Brigadier General Jubal Early's brigade in a counterattack that defeated a major Federal assault.

[4] At the Battle of Chancellorsville, the 8th Louisiana Infantry was assigned to Brigadier General Harry T. Hays' brigade in Early's division and suffered losses of 17 killed, 64 wounded, and 89 missing.

[17] After a Union attack captured Marye's Heights on 3 May, Hays' brigade was able to escape with only the loss of 27 stragglers.

[18] On 4 May at Salem Church, the brigades of Hays and Brigadier General Robert Hoke attacked and broke through the first Union line.

[4] The Cemetery Hill attack was carried out at dusk by the brigades of Hays and Colonel Isaac E. Avery.

Early declined to send supporting troops and Union counterattacks soon ousted the Confederates from the position.

However, at 5 pm, in the Second Battle of Rappahannock Station, Union Brigadier General David Allen Russell's division successfully stormed the bridgehead and seized the pontoon bridge before the bulk of its defenders could escape.

Including a minor setback at Kelly's Ford, Confederate losses numbered 2,023, while there were only 419 Federal casualties.

Fighting in dense woods, Hays' brigade blundered into a numerically superior Federal concentration and took a severe beating, losing an estimated one-third of its strength.

[23] At the Battle of Spotsylvania on 12 May, a powerful Union column overran a position called the Mule Shoe and Hays' brigade helped seal off the breakthrough.

The 8th Louisiana Infantry fought at the Battle of Cold Harbor and Lieutenant Colonel Lester was killed on 2 June.