Hello, I recall reading that the Art of War by Henri Jomini was a text that was used by the Americans and influenced future Civil War commanders like Lee (whom was very Napoleonic in respect to tactics) and Stonewall Jackson (also very Napoleonic in almost every way).
So to what extent was Jomini an influence in the tactical upbringing of the commanders of the Civil War?
Jomini was first introduced at West Point by two men: D.H. Mahan, a professor who led a "Napoleon Club" that studied the Frenchman's campaigns through a Jominian lens, and Henry Halleck, who translated Jomini's works but also modified its content.
Halleck's translations were taught to the class of 1846, which included Stonewall Jackson, George McClellan, and A.P Hill. Lee and Grant were already graduated--Grant later confessed to never having read Jomini.
Generally speaking, the Civil War was not fought according to Jominian precepts. Staff work was often deficient, decision-making was convoluted, and battle plans tended towards the Napoleonic-style annihilation of enemy forces.
The Confederate Army broke with Jomini in its continued offensives into Northern territory, which is not a part of Jomini's defensive scheme
The Union Army broke with Jomini with its early-war focus on slow advances and "keeping the army well in hand" and wary of surprise counter-offensives. The late-war strategy of civilian destruction also ran counter to Jomini.
I would not rush to define Civil War tactics through a Jominian lens. After all, everybody was learning a skewed, Americanized version of Jomini. It's exceedingly difficult to draw a pure line between his theories and Civil War battlefield practices.
There's certainly more here to discuss and I've cut many thoughts short. I hope this helps in some small way! I don't mind follow-up questions, either.
Best, Sam
(Civil War historian by profession)