The Federals began their long-awaited second drive toward Richmond nearly one year after the fall of Fort Sumter. It would be a massive undertaking, involving more troops than had ever been assembled in a single field army in the country's history, and would bring a comparable response from the Confederates. The campaign saw the extensive use of fortifications by both sides for offensive as well as defensive purposes, but they never became the key factor in determining the outcome of the campaign. While the Confederates built complex works along the Warwick River during the Yorktown phase of the campaign, all the other earthworks on the Peninsula were much simpler and of more limited usefulness. No previous operation of the eastern campaigns had utilized fortifications so much, yet the ability of engineers, field commanders, and ordinary soldiers to use them as a weapon to achieve victory was still undeveloped.
Whether or not an army used earthworks was often determined by the attitude of its commander, and George McClellan was, by nature, inclined to rely on them. He had graduated second in the West Point class of 1846 and thus secured a coveted appointment in the Corps of Engineers. The young lieutenant quickly prepared for service in the Mexican War, where he helped plan and build the battery emplacements that softened the Mexican position at Chapultepec. McClellan was one of three members of a commission sent to observe operations during the Crimean War of 1854–56. He was impressed by the Russian defense of Sebastopol and came away from the Crimea a firm believer in the efficacy of field fortifications.1
McClellan's willingness to take fortifications seriously as a major element in operations was tied to his innate conservatism as a field commander. Not only did his political leanings lead him to admire elite Southerners and view the war as a conflict for the restoration of the status quo, with no interference in the institution of slavery, but he had an almost overwhelming fear of battlefield loss. McClellan conceived of warfare as an art, the aim of which was to outmaneuver his opponent so as to gain tactical and strategic advantage with minimal loss of men. He was cautious to a fault and prone to use earthworks as a substitute for action rather than as an aid to further advances.2