After reading a novelization of this interesting woman's life, I was moved to find an actual biography. In fact, my public library has two: this is the earlier (1995), and clearly the result of an impressive amount of original research. Seymour appears to have had no difficulty with the multilingual nature of his archival sources (few would argue that the most interesting period of Montez' life, as well as the best-documented by letters, was when she was the mistress of King Ludwig of Bavaria; she also spent periods of time in French-speaking Europe, and she posed as Spanish, which meant she had at least some command of the Spanish language). I enjoyed Seymour's measured but lively discussion of all phases of the life of Montez (aka Eliza Gilbert, aka the Countess of Landsfelt, aka any number of other occasional names).
At the end of this account, I couldn't help feeling a little sorry for Lola. She was celebrated during her life for her physical beauty, for an apparently ungovernable temper, and for a blithe disregard for "middle-class morality", as Alfred Doolittle would say. What becomes rather clear is that she earned all of this reputation before she was thirty, making far more than most women would have of the very limited opportunities she was offered by her birth (illegitimate) and upbringing (peripatetic, without secure financial resources, and with little or no care or love from her nearest surviving relative, her mother). It was apparently in her 30s that she grew up quite a bit, discovering that she had more reliable talents - decent acting, and quite good public speaking - than the limited quasi-dancing and scandalous acquisition of rich lovers that had sustained her as a younger woman. She also, apparently sincerely, turned to religion, of the Protestant variety. Her near monomania on the subject of Jesuit plots against her is one of the less attractive features of the story, and one I do not fully understand, though it appears to be very much intertwined in European politics of the day. Seymour downplays the influence she claimed to have had over the liberalization of Bavaria during the time when she was Ludwig's mistress, which was also the time of the 1848 revolutionary movements across Europe.
Though she may have grown up a bit when she went to America, according to Seymour's sources, Lola did not by any means stop trading on her scandalous status; either completely deliberately (she is perhaps the first woman ever to be photographed holding a cigarette, in New York in 1851) or by her continuing failure to control her temper (her Australian acting tour was only one of the occasions on which she created an incident by taking a riding whip to someone). More troublingly, even as she developed a reputation for being very generous with both money and time to humble people, she was also capable of downright mean behaviour, such as assembling an American acting company to go to Australia, and then dumping them completely after their first engagement, leaving them to find their own way home. Unfortunately, she also appears to have remained an inveterate liar throughout her life, although Seymour's quotations suggest she may have become self-aware about that towards the end.
Though he documents Montez' affiction by migraines throughout her life, Seymour does not give a medical diagnosis of what carried Lola off at the age of 39. According to Wikipedia, it was syphilis.
I am impressed with Seymour. He's not an academic (the writing of this volume was financed by his extensive winnings on Jeopardy) but he has the instincts of one, and he got this book published in a nice edition by Yale University Press. He also had the grace to donate all his research materials to a University library so that others could delve even deeper. Good for him.