Ah, Santa Anna, the Napoleon of the West. He's a fascinating character. It's been a few years since I did any reading on him so this will be a bit sketchy and hew relatively closely to the question of power and the presidency.

The first thing to note is that Santa Anna was no democrat. At the time the president was elected by the provincial legislatures, who proved easily malleable. Alternatively, the office could simply be seized via coup, which was also common. Which is not to say that Santa Anna was necessarily always unpopular - he took full public advantage of his victories and his ally José María de Tornel was an effective propagandist. The flamboyant nicknames and gestures (including a funeral for his amputated leg) were not just vanities: in an era before formalised political parties/traditions, such public relations were powerful in establishing an individual's legitimacy.

It's also worth noting that while Santa Anna coveted the presidency, and its spoils, he had no appetite for governing. A number of his eleven stints in office were extremely brief; he would tire of the office after a few months and then retire to his Veracruz estates, leaving a puppet in his place.

But then Veracruz was central to Santa Anna and his ability to seize power. This was the era of regional strongmen (caudillos) in Mexico - the likes of Nicolás Bravo, Anastasio Bustamante, Guadalupe Victoria, Manuel Gómez Pedraza, etc - who competed with each other for highest office. Santa Anna was the Big Man in Veracruz and this served ably as his powerbase for decades. In this light, and with central government authority extremely weak, Santa Anna was merely one amongst many regional bosses. Albeit a particularly capable one.

So in terms of capturing power it was a combination of extensive patronage, military coups and powerful public relations. These allowed Santa Anna to navigate the treacherous world of Mexican politics with skill.

That he was able to do so over the space of decades leads to the 'Age of Santa Anna' label. Historians still argue as to the degree to which Santa Anna was the cause of Mexico's instability or merely emblematic of it. But this was an anarchic period (thanks in part to Santa Anna) in which the foundations of the Mexican nationstate were just taking shape and there was room for military strongmen to carve out power for themselves.

Will Fowler's Santa Anna of Mexico is probably the best, if sympathetic, English-language biography of the caudillo around today.