US Civil War doctrine debate

This page is for the purposes of Canadian Forces College Experiential Learning Visit in support to the Joint Command and Staff Programme.

Warfare had gone through many cycles of Offensive/Defensive primacy before the US Civil War.  In 1494, Charles VIII of France brought a rapid end to what had been an era of Defensive primacy with the introduction of mobile horse drawn artillery.  In his six month campaign through Italy rendered fortified cities obsolete and signaled the end of large dense pike formations. (Boot, 2006)  Warfare entered an Offensive primacy era that would last until the 17th century when new technology allowed for improvements in fortifications to blunt the power of artillery, leading again to a Defensive era which would last for over 100 years.  In the late 18th century once again an Offensive era would again arise with Fredrick the Great and the birth of what could be viewed as manoeuvre warfare.  The Napoleonic Wars (1805 - 1815) were an era of Offensive warfare primacy, with rapid mobility and organizational innovations once again (https://fas-polisci.rutgers.edu/levy/articles/1984%20Offense-Defense.pdf).  It was the Napoleonic Wars that would shape the thinking of pre-Civil War American theorists.

The most prominent and influential pre-Civil War American military theorist was Dennis Hart Mahan (https://en.wikipedia.org/wiki/Dennis_Hart_Mahan).  Mahan was a professor at West Point and chairman of the famous "Napoleon Club".  In this position he was highly influential in the development of many of the most senior officers in the US Civil War (e.g. Robert Lee and George Mclelland).  Rather than adopt European military theory blindly, Mahan recognized that warfare was once again entering into a potential shift in theoretical foundations.  Offensive warfare had been in primacy for nearly a century; however, modern technology was signaling a potential shift once again.  The inventions of rail, telegraph, better artillery and infantry weapons all pointed towards an ability to rapidly project military mass; however, the lethality and range of that mass was highlighting a need to adopt a more conservative approach to both flanking and frontal infantry manoeuvres.  Mahan was a military engineer by academic background and emphasized the employment of field fortification and defensive warfare as key to shaping a battle until such a point that decisive attack could be carried out.  Building on the ideas of prominent European military theorists such as Jomini, Mahan created an influential case for a uniquely American way of warfare that emphasized "active defence" and a hasty field fortifications.

The US Civil war in many ways became a test bed and a collision between the Offensive primacy warfare of the Napoleonic era and what would emerge as a Defensive primacy era that would last until the the beginning of the Second World War with the invention of mechanized warfare and military airpower.  The Confederacy, Robert E Lee in particular favoured Offensive warfare of seeking decision at the time and place of his choosing.  The Union began the war very conservatively favouring Defensive styles of warfare.  As the war progressed it became apparent that warfare was signaling a significant pivot once again.  Lee's Offensive strategies led to early and dramatic victories; however, they were not supported by institutional capacity of the South - no victory by the Confederate forces in the first 2 years of the Civil War was truly strategically decisive, even if they were tactically and operationally so.  The more Defensive warfare styles of the Union forces surrendered freedom of manoeuvre to the Confederate forces; however, they were also very effective in creating attrition that the South could not sustain.

Gettysburg itself is a tactical microcosm of the shift in the character of land warfare.  The battle began with rapid manoeuvre until the Union forces established a defensive line along the famous hook.  Lee attempted turning battles to the south; however, never was able to effectively break the union line.  Then in one last gambit attempted a frontal assault directly at the middle of the Union line with Picketts famous charge.  One could argue that Pickett's Charge was prescient of the First World War where the press of military mass in the form of infantry would be doomed to fail in the face of emerging modern firepower.  At Gettysburg 18th and 19th century Offensive primacy met 20th century industrial warfare and the result was a signal that Defensive primacy was once again on the rise.  The South would never recover from Gettysburg and late in the war the battles around Petersburg would look far more like trench warfare of the First World War than the Napoleonic Wars.

Looking at the contemporary operating environment, we have been in an era of Offensive Primacy since 1939.  With recent observations coming out of the war in Ukraine a significant unknown is whether we are seeing an anomaly or are we on the cusp of another major shift in the character of warfare?