You wait ages for a monograph that solves a persistent historical riddle, then two turn up in short order; Anglophone historians of Mexico are living in propitious times. In 2017 Timo Schaefer's Liberalism as Utopia (also CUP) gave us a convincing and well-evidenced framework for understanding a thorny old puzzle: the seismic shifts in nineteenth-century legal–political culture. Now Sarah Osten has provided a compelling and captivating account of an equally difficult, though rather more concentrated, historical problem: the shift from revolutionary conflict to post-revolutionary state in the 1920s. The Mexican state in that decade has been described as ‘a chaotic, multiauthored work in progress … built on the backs of regional governments … all [led by] builders of populist, clientelistic regimes’ (M. K. Vaughan, ‘Pancho Villa, the Daughters of Mary, and the Modern Woman: Gender in the Long Mexican Revolution’, in M. K. Vaughan, G. Cano and J. Olcott (eds.), Sex in Revolution: Gender, Politics and Power in Modern Mexico, Duke University Press, 2007, p. 27). For scholars, teachers and students of Mexico the long 1920s has often been the trickiest phase to tackle – the leap from the 1917 Constitution to the ascendancy of Cárdenas from 1934 is often covered with unseemly, if pragmatic, speed. Now, in the guise of a study in regional politics we have a monograph which goes a long way towards explaining how the national revolution got to the point of institutionalisation. Much of the answer lies in the appropriation or emulation of local institutionalisers, and it is these characters – particularly Felipe Carrillo Puerto, Tomás Garrido Canabal and Carlos A. Vidal, with Plutarco Elías Calles and Álvaro Obregón always lurking in the background – whose political roles form the backbone of the book.

The Mexican Revolution's Wake is an important intervention in three fields: first, and most obviously, the history the Mexican Revolution, and specifically its institutionalisation. While Heather Fowler-Salamini (Agrarian Radicalism in Veracruz, 1920–38, University of Nebraska Press, 1978), Pedro Castro Martínez (Adolfo de la Huerta y la Revolución Mexicana, Instituto Nacional de Estudios Históricos de la Revolución Mexicana, 1992) and others have addressed aspects of this process (and its attendant setbacks and ruptures), few have offered an account of the twin processes of party and state formation in the 1920s with such facility. Second, it is an impressive addition to Mexican regional history, making a case for taking the ‘southeast’ seriously as a political region, while not shying away from the important fractures and variances between its constituent states. Third – and I return to this below – it opens up important questions for historians of the Left.

Osten describes two simultaneous circuits or relationships: the first running from central to peripheral nodes of power, most clearly from Calles (first as interior minister, then as president) to Carrillo Puerto and Vidal, and vice versa; the second encapsulating the regional leaders and their supporters. Thus, where Alan Knight has identified two phases of peasant mobilisation in the revolution, Osten's work goes a long way towards explaining the second. While for Knight the 1910s saw ‘massive peasant mobilisation – sometimes abetted by bourgeois reformists – in opposition to a long-established traditional landlord class … [which] was initially violent, localised, and relatively spontaneous and autonomous’, the 1920s by contrast were characterised by ‘“secondary” peasant movements which responded to increased political opportunity, incitement, and education’ (‘Social Revolution: A Latin American Perspective’, Bulletin of Latin American Research, 9: 2 (1990), p. 189). These movements worked in dialogue – sometimes collaboratively, sometimes antagonistically – with the southeastern socialists profiled by Osten in this volume.

The book takes three detailed local cases – Yucatán, Tabasco and Chiapas, with some analysis of Campeche too – as well as three broader processes: the transregional growth of ‘southeastern socialism’; the de la Huerta rebellion of 1923–4; and the Gómez–Serrano campaign/rebellion of 1926–7. The regional case studies – each complex and distinct – are handled deftly. The commonalities which make the book work as a whole are defined, identified and evidenced with clarity and concision, but nowhere is local detail sacrificed. While there is a substantial literature (though not an enormous amount in English) on Yucatán, the weaving of historiographically ‘odd’ Tabasco and Chiapas into the same narrative is immensely valuable, both for understanding 1920s Mexico and for exploring Mexican regionality.

The rebellions are explained with clarity, hardly a given since the regional impacts of both the de la Huerta and Gómez–Serrano movements were colossal and complex. In places Osten's book must work to illuminate historical uncertainty: was the 1927 uprising simply a presidential campaign that got out of hand? Or rather two campaigns? An accidental armed rebellion? A deliberate, well-planned plot? As Osten puts it, ‘it is impossible to know precisely at what moment the anti-re-electionist movement became an armed rebellion against the Mexican government, or if it ever truly did’ (p. 223). Accusations of disloyalty, especially secret Delahuertista sympathies or activities, were thrown around like confetti. Calles, sphinx-like, bided his time, allowing the anti-re-electionists to think he shared their distaste for another Obregón presidency; many of them died thinking he agreed with them.

The concluding sections of the book tie together the threads present in the case studies to form a bold and compelling revisionist thesis. Far from being failed experiments, or mere local curiosities, Osten shows that southeastern socialisms in fact prefigured the organisational form (though not the ideology, at least not until later in the 1930s) of the Partido Nacional Revolucionario (National Revolutionary Party, PNR)/Partido de la Revolución Mexicana (Mexican Revolutionary Party, PRM)/Partido Revolucionario Institucional (Institutional Revolutionary Party, PRI), as well as absorbing the southeastern leaders’ appreciation of the need for a critical mass of popular support. In fact this process happened while those southeastern socialisms were themselves still evolving: ‘the applicability of the southeastern model of party building to national politics, with or without electoral democracy, was established by 1927’ (p. 233). Vidal, in particular, had the rug pulled out from beneath his feet. And on the ideological point – that is to say, on what ‘socialism’ came to mean when it was appropriated and scaled up by Calles – ‘socialism became the way that politics was done, rather than a coherent core of reformist or ideological commitments’ (p. 244). In the end, socialismo was just a ten-letter word, and one which was ‘becoming rhetorically indistinguishable from “revolution” in national politics’ (p. 207) while ‘the concept of an official “Revolution” was crystallizing, largely negatively defined by an equally abstract “Reaction”’ (p. 206). It is little wonder that competing ‘socialisms’ could by 1927 come to such fatal blows.

Two further comments, neither of which should indicate a shortcoming, merely the kind of thoughts this book has stimulated. First, the near-absence of the anti-secularist Cristero War (1926–9); it does crop up – and in the appropriate places, contextualising the Gómez–Serrano campaign/rebellion for instance – but one is left with a reminder of sharp regional cleavages, and perhaps of the absence of many (any?) national political circuits not mediated through the capital. The painstaking efforts of local anti-re-election campaign organisers in 1926–7 are testament to this structural reality. Second, Osten displays admirable restraint in avoiding (probably anachronistic) projections of political ideology onto movements whose core values remained often vague and usually rather flexible. As a historian of the Mexican Left, it has pushed me to think much more deeply about what ‘the Left’ or ‘Lefts’ might constitute in such circumstances: ideologically-heterodox coalitions were (re)forming around specific issues or events – centre–periphery relations, succession mechanisms, re-election, trade with the United States – which are not, prima facie, mapped easily onto a Left–Right spectrum.

This is a clear, cogent and innovative contribution to the history of post-revolutionary Mexico, offering a plausible, well-evidenced account of how the ruling party eventually came into being, but also reminding us of the many paths not taken in that crucial period of state formation. It is a compelling read with important, frustrating and – in many cases – tragic sub-narratives; highly recommended.