It is no longer necessary to begin a discussion of Civil War diplomacy with a comment about its relative neglect in the historiography. Recent years have seen the publication of numerous monographs and articles on various aspects of the topic. The overseas dimensions of the conflict also have been accorded much attention in recent general accounts of the Civil War era.
A challenge that now confronts diplomatic historians, and the task of this round-table, is to think about how the literature on the Civil War years can be placed onto the broader canvas of American history. Rather than treat the Civil War years in isolation as a peculiar moment in diplomatic history, we might follow the lead of historians of the state, religion, gender, finance, and so on who have seen in the Civil War an epochal moment in which long term trends both culminated and inaugurated.
One promising direction would be to view the sectional conflict, as did Americans at the time, in relation to the persistent struggle to consolidate American independence from the British Empire. Those on either side of the Mason-Dixon Line viewed themselves as continuing the tradition of 1776 and came to see the other in relation to the persistent (and often imagined) British threat: Southerners saw Northern abolitionists as the stooges of British antislavery; Northern Republicans viewed the ‘slave power’ of the South as an Old World, aristocratic clique whose cries of King Cotton and tariff reduction masked lingering economic dependence upon the British.
The Civil War can be seen as the culmination of the American Revolution. It determined the political and economic arrangements that would emerge from an internally contentious postcolonial period. The Union triumph of 1865 consolidated the bonds between the states, thus eliminating what American nationalists long had considered the doomsday scenario: the introduction of balance of power politics into North America through the destruction of the independent union and its replacement with regional confederacies allied with European powers.
The American story mirrors that of other postcolonial societies, such as Latin America in the nineteenth century and Asia and Africa in the mid-twentieth, where internal conflict followed the erosion of colonial rule. In the historical context of the 1860s, we might also reflect upon the confluence of events in North America. The decade not only witnessed the consolidation of the American Union, but also the failed French intervention in Mexico, British devolution in Canada, and the Cuban anticolonial rebellion (beginning in 1868) that foreshadowed the dissolution of Spanish rule. In other words, it was an important moment in North American decolonization. A question that historians might pursue concerns the extent to which these processes were connected to, or even a result of, the sectional conflict in America.
The anti-imperialism of postcolonial America, of course, was inextricably linked to the imperialist processes of westward colonization and overseas expansion. The work of the New Left, particularly LaFeber’s still indispensible The New Empire, remains the starting point for thinking about how the Civil War propelled the new nation on the path of the new imperialism. The Morrill Tariff of 1861 began an age of protectionism in which America’s burgeoning industries would be insulated from their British and European rivals. In financial terms, too, the Civil War fostered the development of Wall Street, which, after the financing the titanic Union war effort, would provide much of the capital required in the colonization and economic exploitation of the American West. In addition to decreasing reliance on British capital and commerce, these economic developments helped to establish powerful interest groups within the United States that would promote commercial expansion in the late nineteenth century.
The synergy between anti-imperialism and imperialism in the Civil War era can be seen in the emergence of a new Monroe Doctrine (indeed, the phrase “Monroe Doctrine” itself became entrenched in the American vocabulary in the 1850s and 60s). The French intervention in Mexico reinforced traditional fears of European meddling in the New World. But the Monroe Doctrine that emerged in this period was more than simply a restatement of anti-imperialism, for American statesmen sought not only to eliminate the French threat in Mexico, but also to turn Mexico into an economic satellite of the United States. Here the connection between internal and external policy is worth commenting upon: as Union leaders intervened in the seceded states of the South, they contemplated newly assertive policies to achieve their objectives in Mexico.
The Civil War serves as a powerful reminder that there was nothing inevitable about the existence of a single American nation. Writing as we do in the present-day context of American global power, we historians must take extra care not to take the nation as a given, nor to project American power back onto the earlier period. After all, the Confederacy reveals the existence of alternative ideas of statecraft and a proslavery nationalism that sat uneasily beside the democratic nationalism articulated by Lincoln.
Foreign observers at the time, of course, were well aware of the protean and contingent nature of the American experiment. To them, there was nothing pre-ordained about the establishment of the American nation – indeed, the more widely held assumption of European liberals in 1861 was that self-determination would triumph in the South. But the Union prevailed. The success of the liberal nation-making project in the United States had profound implications around the globe. Charting the global story of mid-nineteenth century national-formation and nationalism is a challenging task that remains in its infancy. A recent, collaborative examination of Lincoln’s global celebrity suggests that the American story had implications around the globe, fuelling the liberal nationalism that would redefine world politics and international relations. In this light, the Civil War was central not just to the history of the United States, but also to that of the world.
 See, for example, Adam I.P. Smith, The American Civil War (Basingstoke: Palgrave, 2007).
 For an important new study of Anglophobia, see, Sam Haynes, Unfinished Revolution: The Early American Republic in a British World (Charlottesville: University of Virginia Press, 2010).
 David Hendrickson, Union, Nation, or Empire: The American Debate over International Relations, 1789-1941 (Lawrence: University Press of Kansas, 2009)
 Walter LaFeber, The New Empire: An Interpretation of American Expansion, 1860-1898 (Ithaca: Cornell University Press, 1963). For the West, see Heather Cox Richardson, West from Appomattox: The Reconstruction of America after the Civil War (New Haven: Yale University Press, 2007).
 Thomas D. Schoonover, Dollars Over Dominion: The Triumph of Liberalism in Mexican-United States Relations, 1861-1867 (Baton Rouge: Louisiana State University Press, 1978).
 Richard Carwardine and Jay Sexton (eds.), The Global Lincoln (New York: Oxford University Press, 2011).