If today's Army is Jominian rather than Clausewitzian, does this mean that its higher-level doctrinal development is steeped in the Civil War? I think so. Mahan, at West Point, rooted Jominian theory and practice in the minds of a generation of young soldiers, McClellan and Halleck among them.
Yes, the Army talks up Clausewitz and lives up Jomini. Any serving officer could tell you.
In its history texts and teachings, for instance, it reveres Lee and Jackson at the expense of McClellan and Meade. (Lee, Jackson = Clausewitz. McClellan, Meade = Jomini.)
In actual practice, it manages to out-McClellan Mac from day-to-day and war-to-war; at least in terms of what the Republican radicals imagined McClellan and other West Pointers to be. In actual practice, any officer, encouraged to admire Lee and Jackson who then imitates them will have a career of less than one fleeting moment. (I'm thinking not of clever strokes but of naked, hungry and shoeless troops; the summary execution of stragglers; the withholding of operational plans from subordinates; the repeated arrest of senior subordinates; high rates of desertion; frontal assaults on fortified positions while outnnumbered, and similar failings ad nauseum.)
What the Army says it likes and what it does can contradict each other, because a system of rewards and punishments make its real values clear to its members. The war colleges can teach Clausewitz without a downside, because Army life is nurturing and rewarding Jominians.
The disconnects, however, can be viewed from afar with a certain humor. Colin Powell opens the first Gulf War publicly criticizing McClellan and promising never to be like him (or like his pop history persona); our Saudi allies later reveal their continuous complaints to Powell about the excessive time building up before the attack; and they criticize U.S. estimates of the Iraqi army's size as wildly excessive.
The U.S. Army’s doctrinal application of the theories of war at the tactical and operational levels shows that, at its core, it is a Jominian institution.
While leaders of the Army and self-proclaimed civilian experts of military thought prefer to quote Clausewitz when describing current and future operations, it is to the comfort and optimism of Jomini that the U.S. Army continually returns.