Complex sentence: Lomax fought his brigade under the division command of his old classmate Fitzhugh Lee from Culpeper Courthouse through the Wilderness and around Petersburg until promoted to major general in August 1864 when he was assigned to Jubal Early in the Shenandoah Valley.
Split into simpler sentences: Lomax fought his brigade under the division command of his old classmate Fitzhugh Lee from Culpeper Courthouse through the Wilderness and around Petersburg. He was promoted to major general in August 1864, and was assigned to assist General Jubal Early in the Shenandoah Valley.