The Mexican–American War of 1846–8 is, arguably, the forgotten war of North American history. As a glance at library or bookstore shelves in the United States shows, it is easily eclipsed by the Civil War (which it helped to bring about); while in Mexico it is understandably regarded as a national disaster, when, suffering defeat and divisions, the nation lost half of its territory to its expansionist northern neighbour. (That said, the sesquicentenary of 1998 did prompt some innovative research in Mexico, especially focused on the regional impact of the war.) Since the war made the United States a continental power with direct access to the Pacific, US neglect is rather harder to fathom (especially given the US taste for tub-thumping triumphalism: recall that the US Marines’ anthem begins by invoking ‘the Halls of Montezuma …’). But perhaps the lingering sense that it was a predatory war of choice – ‘one of the most unjust ever waged by a stronger against a weaker nation’, as Ulysses S. Grant called it – has somewhat inhibited serious inquiry north of the border.

For these reasons, Peter Guardino's The Dead March is a very welcome addition to the patchy literature. It is particularly welcome as it is deeply researched, written in a clear, uncluttered style, and is the work of a distinguished historian of Mexico who has – as far as I, a paid-up Mexicanist, can tell – fully mastered the US side of the story as well. So, unlike many histories of the war, the account is genuinely bilateral and, as such, it shows that the two belligerents were much more alike than many casual observers – or even serious historians – might suppose. The US army did not roll over a bunch of demoralised Mexican peons: the Mexican army fought doggedly, despite being ill-provisioned and seriously out-gunned (regarding both artillery and small arms). The US army, combining better-off volunteers swept up in the initial war-fever and desperate men raised from the ‘mobile and rootless’ poor of the big northeastern cities (p. 36), was multi-ethnic, badly disciplined, prone to desertion, and – as US commanders like Winfield Scott admitted – often rapacious in its treatment of the hapless civilian population (p. 107). The senior officers jockeyed for pre-eminence, while the resentful rank-and-file were subjected to harsh corporal punishment.

Contrary to several standard accounts, Guardino shows that Mexico did not lose the war because it lacked patriotic sentiments (the Mexicans being merely ‘imaginary citizens’, in Fernando Escalante Gonzalbo's neat but misleading phrase: Ciudadanos imaginarios, El Colegio de México, 1992); after all, the most notable defection of the war involved the San Patricios – Irish-American Catholics who deserted the US army and went over to the enemy (pp. 250–63). Rather, Mexico lost because the United States had greater economic resources (its per capita income was three times that of Mexico), it supplied its forces more efficiently, by land and sea, and, for the duration of the war, it maintained a measure of political cohesion. In contrast, the Mexican government faced chronic bankruptcy; it could not adequately provision its forces, especially across the vast arid expanses of the northeast, where the initial invasion occurred; and its politicised generals squabbled and, at critical moments, betrayed one another.

Guardino briskly narrates the story of the two main campaigns and the key battles – Resaca de Palma, Palo Alto, and Buena Vista in the northeast and Cerro Gordo in central Mexico – followed by the hard-fought conquest of the capital (and the serious anti-American riots which ensued [Chapter 7]: further evidence that the Mexican plebs were not supinely unpatriotic). But, unlike traditional accounts of the war, the book is couched in the ‘new military history’ style, which means that, rather than focusing squarely on the generals marshalling their men on the chessboard of battle (what John Keegan called ‘Napierite’ military history: The Face of Battle, Harmondsworth, 1978, pp. 35–40), Guardino addresses the experience of the rank-and-file (on both sides), describing, often in evocative detail, their origins, conduct, grievances and prejudices. Conventional military history thus jostles with cultural analysis: US notions of masculinity; Mexican fears of Protestant advance, which clashed with US stereotypes of Catholic superstition and backwardness, stereotypes which legitimised the widespread looting of churches.

Antonio López de Santa Anna, the villain of the piece for many Mexicans, emerges quite well from these pages. He was a competent tactician and, more important, a sound strategist, who, in the face of huge obstacles – government bankruptcy, lack of military resources, popular suspicion of military recruitment, and sharp political divisions – nevertheless managed to maintain the Mexican war effort, both conventional and guerrilla, thus confounding US expectations of a short, sharp, easy war. (As President James K. Polk, the devious instigator of the war, insouciantly convinced of innate US superiority, had wrongly assumed it would be. In which respect, of course, he set a precedent which later US administrations would follow, in the Philippines, Nicaragua, Vietnam and Iraq.)

Perhaps the most intriguing and suggestive big argument of the book is that the mid-nineteenth-century United States and its Mexican neighbour were, in several respects, strikingly similar: they were new nations-in-formation, regionally diverse, familiar with violence and vigilantism; the armies’ ranks were filled with the poor and destitute; the officers squabbled for precedence; some also aspired to high political office – and they included not just the notorious caudillos of Mexican history, but also US presidents-to-be like Grant and Zachary Taylor. Guardino's excellent book thus reminds us that, for all the talk, then and since, of American exceptionalism (and superiority), the new republics of the Americas had a good deal in common. Of course, divergence became more marked after 1848, in part because of the war itself, which, on the eve of the California gold rush, made the United States a continental power; in addition, it helped provoke the American Civil War and, in the process, the creation of a stronger state and a burgeoning industrial economy. In Mexico, too, defeat prompted intense political debate and polarisation, leading to serious civil strife and renewed foreign (French) invasion – which, this time around, the Mexicans successfully repulsed. Clearly, the Mexican–American War was a decisive turning point for both countries; and The Dead March provides a thorough, convincing and readable account of its dramatic course and decisive outcome.