Kruse's Lortzing Biography (1899) online, and more Lortzing Freebies!

George Richard Kruse is one of the first biographers of Lortzing and his work cannot be underestimated. He published Lortzing's letters in three editions and several short articles. Also he published a great deal of Lortzing's Operas with extensive, "in der Beschränkung zeigt sich nicht der Meister" prefaces and he wrote two biographies.
One of them, published in 1914, is republished on this website, but the older biography of 1899 is, IMO, better. Some illustrations and examples of music and a text less focused on the sentimental aspects of the "undervalued genius", exploited by his publishers, but more on the musical greatness of Lortzing, which should be, after all, what counts.

Now the good news is that this biography has been digitized recently by the Internet Archive, so you can read it online or download the pdf to your computer.

There is more: at the Internet Archive you find more Lortzing freebies: Opera scores with some misspellings (e.g. "bauberoper" "for "zauberoper", but who cares), the French version of "Die beiden Schützen" (Les Méprises) and the libretto of "Zar und Zimmermann" (you can also find the piano score) published by Wittmann - with a very good preface. (Wittmann's Lortzing biography is to be published on this website, currently work in progress).

Kruse's publication of Lortzing's letters (though surpassed now by I. Capelle's out-of-print publication) are here and here.

Finally: piano scores of Lortzing's most popular operas are at the International Music Score Library Project.