Editor’s Note: The following is excerpted from A Savage War: A Military History of the Civil War by Williamson Murray & Wayne Wei-siang Hsieh © 2016 by Princeton University Press. Reprinted by permission.

It would take until the winter of 1863/64 for Grant to formulate a victorious Federal military strategy of overwhelming and coordinated military pressure across the whole breadth of the Confederacy’s land and sea frontiers, and a full year’s worth of campaigning between 1864 and 1865 to execute that strategy. Nevertheless, one should not believe that the Federal cause saw a complete absence of strategic planning at the outset of the war. In what the Northern press later dubbed the Anaconda Plan, Scott had proposed a Union military strategy early in the war combining a naval blockade with a waterborne expedition down the Mississippi “to clear out and keep open this great line of communication in connection with the strict blockade of the seaboard, so as to envelop the insurgent States and bring them to terms with less bloodshed than by any other plan.” Union naval power would also seize New Orleans at the Mississippi’s mouth, while riverine transport would allow the proposed expeditionary force to turn Confederate positions. Scott estimated in May 1861 that the Mississippi expedition would require approximately 60,000 soldiers, supported by forty steam transports and twelve to twenty gunboats.

Later that month, in a missive to his future replacement, McClellan, Scott adjusted his estimate and called for a slightly larger force—roughly 80,000 men, divided into two columns, one spearheaded and supported by gunboats, while the second column marched in parallel via land. Scott asked McClellan for his military opinion on how many troops would be necessary for this campaign, and for advice on the composition of the proposed river fleet, but McClellan never properly replied. Perhaps the senior general, however, had reminded the self- styled “Young Napoleon” of how he had utilized sea power to great advantage during the Vera Cruz campaign, in which McClellan had served as a lieutenant.

Whatever the source of the idea, the younger general early on recognized the potential advantages of Union sea power. He called for a naval force to help protect Cairo as early as April, and he also supported Commander John Rodgers’s early efforts to build a fleet of river gunboats. Shortly after he moved east to take command of the Army of the Potomac, McClellan also proposed in his first written campaign plan of 2 August that “an essential feature of the plan of operations will be the employment of a strong naval force, to protect the movement of a fleet of transports, intended to convoy a considerable body of troops from point to point of the enemy’s seacoast; thus either creating diversions and rendering it necessary for them to detach largely from their main body in order to protect such of their cities as may be threatened; or else landing and forming establishments on their coast at any favorable places that opportunity might offer. This naval force should also cooperate with the main army in its efforts to seize the important seaboard towns of the rebels.”

In his use of sea power, McClellan revealed a skepticism of the value of committing all military efforts to a decisive and climactic battle and a recognition of the importance of mobility and logistics. He recognized that Union naval superiority, if coastal defenses could be overcome, gave its armies secure lines of communications to the Confederacy’s littoral regions, including many of its most important cities. Even more importantly, mastery of the sea could provide Federal forces both operational flexibility and the potential for surprising Confederate defenders, which could help compensate for the Confederacy’s interior lines of communication (that is, the Confederacy’s ability to use its internal rail network to reinforce threatened points more quickly than could the Union mass its forces in response). During both their prior wars with the United States, the British had ably exploited such advantages. In the Revolution, the Royal Navy had doomed George Washington’s defense of New York City in 1776, and in the War of 1812, its domination of the Chesapeake had played a crucial role in Washington’s fall. The US Army Corps of Engineers (of which McClellan had been a proud member as a lieutenant) had constructed a system of seacoast fortifications designed in large part to defend the republic from British joint operations in the event of a third war with England. While the British example indicated that sea power could not by itself win a war, the Union’s final set of victorious campaigns in 1864–65 included operations to capture the important port cities of Mobile and Wilmington, and Grant’s original campaign plan included an important subordinate expedition to attack Richmond from the southeast via a seaborne expeditionary force, led by Butler.

The Richmond expedition of 1864 followed in broad terms McClellan’s own strategy for a seaborne invasion force to turn the Confederate defenses between Washington and Richmond and allow the Union to advance on the secessionist capital from the direction of the Peninsula between the York and James Rivers southeast of Richmond. However, despite the promise of that line of operations, Butler’s expedition failed in large part due to the same reasons McClellan’s Peninsula Campaign collapsed after the Seven Days battles—namely, both generals proved ineffective field commanders. While McClellan had real strategic vision, his August memorandum also revealed the tendency to overestimate his opponents’ strength that would help sabotage his own march on Richmond. McClellan’s memorandum called for a great host of 273,000 men with 600 guns—a fantastic and unrealistic figure. In his mind, such numbers were a necessity, since less than a week later, he assessed Confederate strength opposite his to be at least 100,000 men, outnumbering his own 2-1. In reality, the Confederates would exert great energies to increase their numbers, but could not even manage to attain a goal of 60,000 soldiers. While McClellan’s defenders continue to cite the faulty intelligence estimates provided to Little Mac on Confederate dispositions, the Union commander should have realized that in light of the Confederacy’s material inferiority, it was fantastic to believe Confederate forces severely outnumbered his own.

In this original formulation, McClellan planned that after everything had been prepared, his vast army would move on Richmond and then on to Charleston, Savannah, Montgomery, and New Orleans. Additional supporting troops would follow to occupy the cities that fell into Union hands and secure lines of supply. While McClellan aimed to coordinate the primary army’s campaign with other separate Federal efforts down the Mississippi River, along the Confederacy’s coast, in the Tennessee-Kentucky area, and in Missouri, those operations would be purely subsidiary campaigns to draw Confederate attention away from the main effort under McClellan’s personal command. While Grant’s winning strategy would eventually balance both the Eastern and Western theaters, McClellan, even at his most innovative, tended to overprioritize Eastern operations. The pressures of the Peninsula Campaign would only exacerbate his problematic tendency to focus on operations he personally directed.

Finally, like his former commander, Scott, McClellan did not neglect political prerogatives in the planning of his military campaign. During his great campaign, McClellan intended that his Northern troops would leave Confederate civilians, their property, and slaves untouched, so that the Union would be restored to its antebellum state without bitterness. Historians continue to debate the depth of anti-slavery sentiment among Northerners at this early stage of the war, but while McClellan’s conservative views on slavery and emancipation represented a sizable proportion of public opinion in the loyal states, it also clashed with the antislavery tendencies of Republicans, whose views hardened after secession. More importantly, McClellan’s political assessment assumed more Unionist sentiment in the Confederacy than actually existed. Lincoln himself had acknowledged during the 1860 presidential election the constitutionally protected status of slavery in the states where it already existed, and simply protecting slavery from military force during the war would do little to allay Confederates’ long-term concerns about the safety of their institution. Regardless, whatever the exact state of public sentiment in the Union and the Confederacy at the start of the war, McClellan himself recognized that his conservative political strategy could only succeed if the war did not become a prolonged and bloody struggle. To prevent that outcome, McClellan’s military strategy would have to bring the war to a successful conclusion during the 1862 campaigning season.

However, in late summer, Scott remained general in chief, and McClellan’s views of strategy remained private advice he furnished the president. McClellan would spend months undermining his superior’s position, but Scott would not finally depart the scene until 1 November. Furthermore, while McClellan early on recognized the value of joint operations and the flexibility provided by mastery of the sea, he never fully appreciated the strategic potential of a blockade of the Confederacy. Fortunately for the Union, Scott retained his position as general in chief long enough to set in motion joint army-navy operations in fall 1861 that would have important long-term results in supporting the Union blockade of the Confederacy.