I think First Bull Run might be classified as a major victory for the Confederates.
Otherwise, we're probably talking about Lee's Seven Days Battles in Summer 1862.
First Bull Run (or First Manassas) in Virginia. It was a Confederate victory.
The First major battle was Bull Run, where an expected Union victory was turned into a defeat
Antietam was the first major battle during the Civil War that actually turned the South away from attacking the North. Very few Southern forays into the North occurred after Antietam. The last, Gettysburg, ended in disaster for the South.
Although the fort, commanded by Major Robert Anderson, never surrendered to the forces of the Confederacy it was abandoned after a seige of 567 days. So a technical victory for the South.
The outcome of the First Battle of Manassas, or First Bull Run was a Confederate victory. The Battle of Shiloh indicated the war would be long and bloody.
During the American Civil War, the South gained confidence with each major victory that occurred, particularly from 1861 to 1863. Of special significance for Southern confidence was the South's victory in the first major battle of the war, the First Battle of Bull Run in July 1861.
Tennessee
Coldharbour in the Virginia theatre, or Kennesaw in the Western theatre, if you classify that as a major victory.
Tennessee
The Battle of the River Plate, 1939.
fort ticonderoga
Which battle was the first major victory for american troops in ww1
Fort Henry - not too difficult, as it was half under water. Shiloh might be classified as the first major victory.
the Continental Army's first major victory was at the battle of Saratoga.
ANSWER The South.
Toulon
The battle of Midway.